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Certificate of Analysis, ROCKLABS Reference Material OxL93, 19 August 2011. Page 1 of 6.

World Leaders in Sample Preparation Equipment,

Automated Systems and Certified Reference Materials

P.O Box 18-142, Glen Innes 1743 Auckland, New Zealand.

P 64 9 634 7696 F 64 9 634 6896 E [email protected]

www.rocklabs.com

Certificate of Analysis

Reference Material OxL93

Recommended Gold Concentration: 5.841 µg/g

95% Confidence Interval: +/- 0.053 µg/g

The above values apply only to product in jars or sachets which have an identification number

within the following range: 248 364 – 250 944.

Prepared and Certified By: Malcolm Smith BSc, FNZIC

Rocklabs Reference Materials

40 Oakford Park Crescent, Greenhithe

Auckland 0632

NEW ZEALAND

Email: [email protected]

Telephone: +64 9 444 3534

Date of Certification: 19 August 2011

Certificate Status: Original

Available Packaging: This reference material has been packed in wide-

mouthed jars that contain 2.5 kg of product. The

contents of some jars may be subsequently

repacked into sealed polyethylene sachets.

Origin of Reference Material: Basalt and feldspar minerals with minor

quantities of finely divided gold-containing

minerals that have been screened to ensure there

is no gold nugget effect.

Supplier of Reference Material: ROCKLABS Ltd

P O Box 18 142

Glen Innes

Auckland 1743

NEW ZEALAND


Website: www.rocklabs.com


Description: The reference material is a light grey powder that has been

well mixed and a homogeneity test carried out after the entire

batch was packaged into wide-mouthed jars. There is no soil

component. The product contains crystalline quartz and

therefore dust from it should not be inhaled.

The approximate chemical composition is:

(Uncertified Values)

%

SiO2 58.70

Al2O3 17.16

Na2O 4.92

K2O 5.25

CaO 3.67

MgO 3.34

TiO2 0.95

MnO 0.06

P2O5 0.25

Fe2O3 4.89

L O I 0.35

Intended Use: This reference material is designed to be included with every

batch of samples analysed and the results plotted for quality

monitoring and assessment purposes.

Stability: The container (jar or sachet) and its contents should not be

heated to temperatures higher than 50 °C. The reference

material is stable, with weight changes of less than 0.5 % at

extremes of naturally occurring temperature and humidity

conditions.

Method of Preparation: Pulverized basalt rock and feldspar minerals were blended

with finely pulverized and screened, gold-containing

minerals. Once the powders were uniformly mixed the

composite was placed into 2581 wide-mouthed jars, each

bearing a unique number. 54 jars were randomly selected

from the packaging run and material from these jars was used

for both homogeneity and consensus testing.


Homogeneity Assessment:

An independent laboratory carried out gold analysis by fire assay of 30 g portions,

using a gravimetric finish. Steps were taken to minimize laboratory method variation

in order to better detect any variation in the candidate reference material.

The contents of six randomly selected jars were compacted by vibration (to simulate

the effect of freighting) and five samples removed successively from top to bottom

from each jar. In addition, five samples were removed from the last jar in the series.

A sample was also removed from the top of each of the 54 jars randomly selected

from the 2581 jars in the batch. The results of analysis of the 89 samples (randomly

ordered and then consecutively numbered before being sent to the laboratory)

produced a relative standard deviation of 0.6 %.

Analytical Methodology:

Once homogeneity had been established, two sub-samples were submitted to a

number of well-recognized laboratories in order to assign a gold value by consensus

testing. The sub-samples were drawn from the 54 randomly selected jars and each

laboratory received samples from two different jars. Indicative concentration ranges

were given. All laboratories used fire assay for the gold analysis, with most using an

instrument finish and 14 using a gravimetric finish.

Calculation of Certified Value:

Results for gold were returned from 44 laboratories. Statistical analysis to identify

outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO

5725-2: 1994. Assessment of each laboratory’s performance was carried out on the

basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1.

Details of the criteria used in these examinations are available on request. As a result

of these statistical analyses, five sets of results were excluded for the purpose of

assigning a gold concentration value to this reference material. A recommended

value was thus calculated from the average of the remaining n = 39 sets of replicate

results. The 95 % confidence interval was estimated using the formula:-

X ± ts/√n

(where X is the estimated average, s is the estimated standard deviation of the

laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-

1 degrees of freedom). The recommended value is provided at the beginning of the

certificate in µg/g (ppm) units. A summary of the results used to calculate the

recommended value is listed on page 4 and the names of the laboratories that

submitted results are listed on page 5. The results are listed in increasing order of the

individual laboratory averages.

Statistical analysis of the consensus test results has been carried out by independent

statistician, Tim Ball.


Summary of Results Used to Calculate Gold Value (Listed in increasing order of individual laboratory averages)

Gold (ppm)

Sample 1 Sample 2 Average

5.289 5.744 5.517

5.506 5.589 5.548

5.68 5.43 5.555

5.54 5.60 5.570

5.66 5.62 5.640

5.727 5.649 5.688

5.54 5.86 5.700

5.73 5.68 5.705

5.78 5.64 5.710

5.642 5.840 5.741

5.79 5.73 5.760

5.726 5.811 5.769

5.743 5.800 5.772

5.73 5.82 5.775

5.66 5.94 5.800

5.850 5.811 5.831

5.815 5.850 5.833

5.85 5.83 5.840

5.850 5.833 5.842

5.884 5.801 5.843

5.84 5.86 5.850

5.885 5.825 5.855

5.87 5.84 5.855

5.83 5.89 5.860

5.87 5.88 5.875

5.94 5.89 5.915

5.91 5.92 5.915

5.947 5.884 5.916

5.93 5.96 5.945

5.940 5.99 5.965

5.94 6.00 5.970

5.94 6.00 5.970

5.965 5.990 5.978

5.95 6.09 6.020

6.04 6.00 6.020

6.025 6.020 6.023

6.02 6.03 6.025

6.04 6.06 6.050

6.49 6.19 6.340

Average of 39 sets = 5.841 ppm

Standard deviation of 39 sets = 0.164 ppm

Relative standard deviation = 2.8 %

95% Confidence interval for average = 0.053 ppm

Note: this standard deviation should not be

used as a basis to set control limits when

plotting results from an individual laboratory.


Participating Laboratories

Australia ALS Minerals, Kalgoorlie

ALS Minerals, Orange

ALS Minerals, Perth

ALS Minerals, Townsville

Amdel – Bureau Veritas, Adelaide

Amdel – Bureau Veritas, Kalgoorlie

Genalysis Laboratory Services, Perth

Independent Assay Laboratories, Perth

SGS Minerals Services, Perth

Standard and Reference, Perth

Ultra Trace – Bureau Veritas, Perth

Burkina Faso ALS Minerals, Burkina Faso

Semafo Burkina Faso S.A.

Canada Acme Analytical Laboratories, Vancouver

ALS Minerals, Val d’Or

ALS Minerals, Vancouver

Bourlamaque Assay Laboratories, Quebec

Loring Laboratories (Alberta) Ltd, Calgary

SGS Minerals Services, Vancouver

SGS Minerals Services, Lakefield

Techni-Lab S.G.B., Québec

TSL Laboratories Inc, Saskatoon

Chile Acme Analytical Laboratories, Santiago

ALS Minerals, La Serena

Côte d’Ivoire Bureau Veritas Mineral Laboratories, Abidjan

Ireland OMAC Laboratories

Kyrgyz Republic Stewart Assay and Environmental Laboratories LLC, Kara-Balta

Mali ALS Minerals, Bamako

New Zealand SGS Minerals Services, Otago

SGS Minerals Services, Waihi

Peru ALS Minerals, Lima

Inspectorate Services Perú S.A.C., Callao

Minera Yanacocha SRL – Newmont, Lima

Russia Irgiredmet Analytical Centre, Irkutsk

South Africa ALS Minerals, Johannesburg

AngloGold Ashanti, Vaal River Chemical Laboratory

Goldfields West Wits Analytical Laboratory

Performance Laboratories, Randfontein

SGS South Africa (Pty) Ltd, Johannesburg

United Kingdom Inspectorate International, Essex

USA ALS Minerals, Reno

Barrick Goldstrike – Met Services

Newmont Mining Corporation, Carlin Laboratory

Zimbabwe Performance Laboratories, Harare

Certificate of Analysis, ROCKLABS Reference Material Ox

Instructions and Recommendations for Use:

Weigh out quantity usually used for analysis and analyze for total gold by normal

procedure. Homogeneity testing has shown that consistent results

when 30g portions are taken for analysis.

We quote a 95% confidence interval for our estimate of the declared value. This

confidence interval reflects our uncertainty in estimating the true value for the gold

content of the reference material. The interval is chosen such that, if the same procedure as

used here to estimate the declared value were used again and again, then 95% of the trials

would give intervals that contained the true value. It is a reflection of how precise the

has been in estimating the declared value. It

laboratory will experience in its own repetitive testing.

Some users in the past have misinterpreted this confidence interval as a guide as to how

different an individual test result should be from the declared value. Some mistakenly use

this interval, or the standard deviation from the consensus test, to set limits for control

charts on their own routine test results using the reference material. Such use i

leads to many apparent out-of

testing, or of the reference material itself.

A much better way of determining the laboratory performance when analysing the

reference material is to accumula

control chart. The appropriate centre line and control limits for this chart should be based

on the average level and variability exhibited in the laboratory’s

provide a clear picture of the long

process, providing good clues as to the causes of any problems. To help our customers do

this, we can provide a free Excel template that will produce sensible graphs, with

intelligently chosen limits, from the customer’s own data.

Legal Notice:

This certificate and the reference material described in it have been prepared with due

and attention. However ROCKLABS Ltd,

no liability for any decisions or actions taken following the use of the reference material.

References:

For further information on the preparation and validation of this reference material please

contact Malcolm Smith.

Certifying Officer

M G Smith BSc, FNZIC

ROCKLABS Reference Material OxL93, 19 August 2011



procedure. Homogeneity testing has shown that consistent results are obtainable for gold




rence material. The interval is chosen such that, if the same procedure as


would give intervals that contained the true value. It is a reflection of how precise the

has been in estimating the declared value. It does not reflect the variability any particular



t an individual test result should be from the declared value. Some mistakenly use


charts on their own routine test results using the reference material. Such use i

of-control points, leading to doubts about the laboratory’s



reference material is to accumulate a history of the test results obtained, and plot them on a


on the average level and variability exhibited in the laboratory’s own

a clear picture of the long-term stability or otherwise of the laboratory testing

providing good clues as to the causes of any problems. To help our customers do

we can provide a free Excel template that will produce sensible graphs, with

telligently chosen limits, from the customer’s own data.

This certificate and the reference material described in it have been prepared with due

CKLABS Ltd, Scott Technology Ltd and Tim Ball Ltd accept



Independent Statistician

Tim Ball BSc (Hons)

1. Page 6 of 6.


are obtainable for gold



rence material. The interval is chosen such that, if the same procedure as


would give intervals that contained the true value. It is a reflection of how precise the trial

reflect the variability any particular


t an individual test result should be from the declared value. Some mistakenly use


charts on their own routine test results using the reference material. Such use inevitably

control points, leading to doubts about the laboratory’s


te a history of the test results obtained, and plot them on a


own data. This chart will

term stability or otherwise of the laboratory testing

providing good clues as to the causes of any problems. To help our customers do

we can provide a free Excel template that will produce sensible graphs, with

This certificate and the reference material described in it have been prepared with due care

and Tim Ball Ltd accept



Independent Statistician

Certificate of Analysis, ROCKLABS Reference Material OxL34, 26 September 2003. Page 1 of 1.



Recommended Gold Concentration: 5.758 µg/g 95% Confidence Interval: +/- 0.071 µg/g

The above values apply only to product in jars or sachets which have an identification number within the following range: The number range is not published on the website

Prepared and Certified By: Malcolm Smith BSc, FNZIC Malcolm Smith Reference Materials Ltd 2 Morriggia Place Auckland 10 NEW ZEALAND Telephone: +64 9 444 3534 Telefax: +64 9 444 7739 Email: [email protected]

Date of Certification: 26 September 2003


Available Packaging: This reference material has been packed in wide-mouthed jars that contain 2.5kg of product. The contents of some jars may be subsequently repacked into sealed polyethylene sachets.

Origin of Reference Material: Feldspars with minor quantities of finely divided gold-containing minerals that have been screened to ensure there is no gold nugget effect.

Supplier of Reference Material: ROCKLABS Ltd P O Box 18 142 Auckland NEW ZEALAND Email: [email protected] Telephone: +64 9 634 7696 Telefax: +64 9 634 6896


Description: The component minerals have been well mixed and a homogeneity test carried out after the entire batch was packaged into wide-mouthed jars to ascertain that the gold is evenly distributed throughout the reference material. There is no soil component. The product contains crystalline quartz and therefore dust from it should not be inhaled.


(Uncertified Values) % SiO2 67.67

Al2O3 19.20

Na2O 10.66

K2O 0.71

CaO 0.29

MgO 0.10

TiO2 0.04

MnO <0.01

P2O5 0.08

Fe2O3 0.55

L O I 0.34

Intended Use: This reference material is designed to be included with every batch of samples analysed and the results plotted for quality monitoring purposes.

Stability: The container (jar or sachet) and its contents should not be heated to temperatures higher than 50 °C. The reference material is stable, with weight changes of less than 0.5% at extremes of naturally occurring temperature and humidity conditions.

Instructions for Use: Weigh out quantity usually used for analysis and analyze for total gold by normal procedure. Homogeneity testing has shown that consistent results are obtainable for gold when 30g portions are taken for analysis. Homogeneity cannot be guaranteed if smaller weights are taken for analysis.

Method of Preparation: Pulverized feldspar minerals were blended with finely pulverized and screened, gold-containing minerals. Once the powders were uniformly mixed the composite was placed into 748 wide-mouthed jars, each bearing a unique number. 30 jars were randomly selected from the packaging run and material from these jars was used for both homogeneity and consensus testing.


Homogeneity Assessment: An independent laboratory carried out all gold analyses by fire assay of 30g portions, using a gravimetric finish with a balance capable of reading to one microgram. Steps were taken to minimize laboratory method variation in order to better detect any variation in the reference material. Homogeneity Assessment Prior to Packaging 30 samples were removed at regular intervals from the prepared candidate reference material prior to packaging into 2.5 kg jars. The results of analysis of the 30 samples produced a coefficient of variation of 0.6%. Homogeneity Assessment After Packaging The contents of three randomly selected jars were compacted by vibration (to simulate the effect of freighting) and five samples removed successively from top to bottom from each of the three jars. In addition, five samples were removed from the last jar in the series. 30 samples were removed from the top of 30 jars randomly selected from the 748 jars in the batch. The results of analysis of the 50 samples produced a coefficient of variation of 0.6%. As the homogeneity testing was carried out using 30g analytical portions, the same degree of homogeneity cannot be guaranteed if smaller weights are taken for analysis.

Analytical Methodology: Once homogeneity had been established, two sub-samples were submitted to a number of well-recognized laboratories in order to assign a gold value by consensus testing. The sub-samples were drawn from the 30 randomly selected jars and each laboratory received samples from two different jars. Indicative concentration ranges were given. Two laboratories used neutron activation and the remainder used fire assay for gold analysis.


30 sets of results were returned from 29 laboratories. Assessment of each laboratory’s performance was carried out on the basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1. Statistical analysis to identify outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994. Details of the criteria used in these examinations are available on request. As a result of these statistical analyses, five sets of results were excluded for the purpose of assigning a gold concentration value to this reference material. A recommended value was thus calculated from the average of the remaining n = 25 sets of replicate results. The 95% confidence interval was estimated using the formula:-

X ± ts/�n (where X is the estimated average, s is the estimated standard deviation of the laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-1 degrees of freedom). The recommended value is provided at the beginning of the certificate in µg/g (ppm) units. A summary of the results used to calculate the recommended value is listed on page 4 and the names of the laboratories that submitted results are listed on page 5.


Legal Notice: This certificate and the reference material described in it have been prepared with due care and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the reference material.

Summary of Results Used to Calculate Gold Value (not related to order of laboratories listed on page 5)

Statistical analysis of both homogeneity and consensus test results has been carried out by an independent statistician.

Gold (ppm)Sample 1 Sample 2 Average

5.350 5.175 5.2635.67 5.33 5.5005.68 5.46 5.5705.58 5.58 5.5805.60 5.59 5.5955.64 5.73 5.6855.6 5.8 5.70

5.70 5.74 5.7205.64 5.86 5.7505.77 5.73 5.7505.734 5.783 5.7595.79 5.75 5.7705.82 5.72 5.7705.65 5.90 5.7755.79 5.79 5.7905.740 5.865 5.8035.820 5.791 5.8065.82 5.80 5.8105.80 5.82 5.8105.89 5.86 5.8755.90 5.91 5.9055.972 5.866 5.9195.91 5.95 5.9305.96 5.97 5.9656.15 6.15 6.150

Average of 25 sets = 5.758 ppmStandard deviation of 25 sets = 0.173 ppm

Coefficient of variation = 3.0 %95% Confidence interval for average = 0.071 ppm


Participating Laboratories Australia Amdel, Adelaide Amdel, Perth

Amdel, Kalgoorlie Becquerel Laboratories, Lucas Heights Genalysis Laboratory Services Pty Ltd, Perth SGS Analabs, Perth SGS Analabs, Townsville Standard and Reference Laboratories, Perth

Brazil Lakefield Geosol Limitada

Canada Acme Analytical Laboratories Ltd, British Columbia Activation Laboratories Ltd, Ontario ALS Chemex, British Columbia ALS Chemex Chimitec, Quebec Bourlamaque Assay Laboratories Ltd, Quebec SGS Lakefield Research Limited, Ontario

SGS XRAL Laboratories, Ontario

Ireland OMAC Laboratories Ltd

New Zealand Amdel New Zealand Ltd, Otago SGS New Zealand Ltd, Waihi

Russia Irgiredmet, Irkutsk Magadangeologia, Magadan Tsnigri, Moscow

South Africa Anglo American Research Laboratories (Pty) Ltd AngloGold, Vaal River AngloGold, West Wits Mintek, Analytical Services Division SGS Lakefield Research Africa (Pty) Ltd

United States of America ALS Chemex, Nevada Barrick Goldstrike Mines Inc, Nevada Newmont Mining Corporation, Nevada

References: For further information on the preparation and validation of this reference material please contact Malcolm Smith.

Certifying Officer Independent Statistician

M G Smith BSc, FNZIC Tim Ball BSc (Hons)

Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 1 of 6.



www.rocklabs.com








within the following range: 412 354– 413 207.

Prepared and Certified By: Brett Coombridge, M.Phil. Chemistry


P.O. Box 316056

Wairau Valley Post Centre

Auckland 0760

NEW ZEALAND


Telephone: +64 9 444 3534

Date of Certification: 18 December 2014










Supplier of Reference Material: ROCKLABS

P O Box 18 142

Glen Innes

Auckland 1743

NEW ZEALAND



http://www.rocklabs.com/

Certificate of Analysis, ROCKLABS Reference Material OxL135. 18 December 2014. Page 2 of 6








%

SiO2 58.86

Al2O3 16.91

Na2O 4.78

K2O 5.32

CaO 3.71

MgO 3.43

TiO2 0.99

MnO 0.06

P2O5 0.26

Fe2O3 5.21

L O I 0.28




Stability: The container (jar or sachet) should not be heated to

temperatures higher than 50 °C. The reference material is

stable, with weight changes of less than 0.5 % at extremes of

naturally occurring temperature and humidity conditions.


with finely pulverized and screened gold-containing minerals.

Once the powders were uniformly mixed the composite was

placed into 854 wide-mouthed jars, each bearing a unique

number. 24 jars were randomly selected from the packaging

run and material from these jars was used for both

homogeneity and consensus testing.


Sampling was performed by Rocklabs Reference Materials and an independent

laboratory carried out gold analysis by fire assay of 30 g portions, using a gravimetric

finish. Steps were taken to minimize laboratory method variation in order to better

detect any variation in the candidate reference material.


Homogeneity: A sample was removed from the top of each of the 24 jars randomly

selected from the 854 jars in the batch. The results of analysis of the 24 samples

(randomly ordered then consecutively numbered before being sent to the laboratory)

indicated 4 results were anomalously low. Analysis of the slags and crucibles related

to these sample showed that excessive gold had been retained, and so the original

reported results for these samples were discarded. The test results of the remaining

20 samples produced a relative standard deviation of 0.9 %.

Settling: The contents of 3 randomly selected jars were compacted by vibration (to

simulate the effect of freighting) and 5 samples were removed successively from top

to bottom from each jar. In addition, 5 samples were removed from the last jar in the

series. No top to bottom gradation in the gold values was observed neither was there

a significant difference between the last jar and the other jars.




testing. The sub-samples were drawn from 24 randomly selected jars and each

laboratory received samples from two different jars.

The samples were analysed for gold by all participating laboratories using fire assay

followed by either gravimetric or instrument finish (AAS or ICP). Indicative

concentration ranges were provided. The amount of sample used in the analyses

varied between laboratories (range 10 - 50g).


The 53 participating laboratories each returned replicate gold results using one finish

method for both samples. Statistical analysis to identify outliers was carried out

using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994. Assessment

of each laboratory’s performance was carried out on the basis of z-scores, partly

based on the concept described in ISO/IEC Guide 43-1. Details of the criteria used

in these examinations are available on request. As a result of these statistical

analyses, 6 sets of results were excluded for the purpose of assigning a gold

concentration value to this reference material. A recommended value was thus

calculated from the average of the remaining n = 47 sets of replicate results. The

95% confidence interval was estimated using the formula:-

X ts/√n












Note: Neither the Standard deviation nor the Confidence interval should be

used as a basis to set control limits when plotting individual laboratory results.

See notes under "Instructions and Recommendations for Use" (pg 6)

Sample 1 Sample 2 Set Average5.315 5.365 5.340

5.195 5.510 5.353

5.459 5.353 5.406

5.35 5.55 5.450

5.535 5.370 5.453

5.580 5.365 5.473

5.505 5.445 5.475

5.503 5.473 5.488

5.478 5.500 5.489

5.47 5.51 5.490

5.56 5.43 5.495

5.488 5.507 5.498

5.522 5.530 5.526

5.554 5.499 5.527

5.503 5.555 5.529

5.52 5.54 5.530

5.53 5.53 5.530

5.64 5.43 5.535

5.53 5.54 5.535

5.51 5.57 5.540

5.48 5.60 5.540

5.523 5.565 5.544

5.53 5.56 5.545

5.558 5.558 5.558

5.53 5.59 5.560

5.540 5.595 5.568

5.47 5.68 5.575

5.582 5.584 5.583

5.457 5.749 5.603

5.63 5.58 5.605

5.61 5.61 5.610

5.68 5.56 5.620

5.60 5.70 5.650

5.71 5.59 5.650

5.615 5.742 5.679

5.743 5.636 5.690

5.633 5.752 5.693

5.68 5.76 5.720

5.745 5.710 5.728

5.858 5.614 5.736

5.718 5.767 5.743

5.615 5.885 5.750

5.816 5.692 5.754

5.77 5.74 5.755

5.69 5.84 5.765

5.76 5.83 5.795

6.01 5.82 5.915


Standard deviation of 47 sets = 0.121 ppmRelative standard deviation = 2.2 %95% Confidence interval for average: = +/- 0.036 ppm

Gold (ppm)



Australia ALS Minerals, Burnie

ALS Minerals, Kalgoorlie


ALS Minerals, Perth


Bureau Veritas Amdel, Adelaide

Bureau Veritas Amdel, Kalgoorlie

Intertek Genalysis Laboratory Services, Perth


SEMAFO Burkina Faso S.A.


ALS Minerals, Val-d’Or


Bourlamaque, Quebec


SGS Minerals Services, Lakefield, Ontario


Techni-Lab S.G.B. Abitibi Inc/Actlabs, Val d’Or

Techni-Lab S.G.B. Abitibi Inc/Actlabs, Ste-Germaine-Boule




Ghana ALS Minerals, Kumasi

Performance Laboratories, Obuasi AngloGold

Ireland ALS Minerals, Loughrea


Laos ALS Geochemistry, Vientiane


Mongolia ALS Minerals, Ulaanbaatar

Namibia Bureau Veritas- Mineral Laboratories, Swakopmund

New Zealand SGS New Zealand Ltd, Otago

SGS New Zealand Ltd, Reefton

SGS New Zealand Ltd, Waihi




Romania ALS Minerals, Rosia Montana


South Africa Acme, Inspectorate M & M, Rustenburg

ALS Minerals, Edenvale

SibanyeGold, Driefontein Operations

Performance Laboratories, Allanridge

Performance Laboratories, Barberton


Turkey Acme Analitik Laboratuar Hizmetleri Ltd, Sirketi

ALS Minerals, Izmir


Barrick Goldstrike – Met Services, Nevada

Inspectorate, Sparks

Newmont Mining Corporation, Carlin

Newmont Mining Corporation, Lone Tree

Newmont Mining Corporation, Twin Creeks

Zimbabwe Performance Laboratories, Ruwa



Weigh out quantity usually used for analysis, and analyse for total gold by normal














leads to many apparent out-of-control points, leading to doubts about the laboratory’s





on the average level and variability exhibited in the laboratory’s own data. This chart will

provide a clear picture of the long-term stability or otherwise of the laboratory testing




Legal Notice:


and attention. However ROCKLABS Ltd, Scott Technology Ltd and Tim Ball Ltd accept


References:




Brett Coombridge (M.Phil. Chemistry) Tim Ball BSc (Hons)

Certificate of Analysis, ROCKLABS Reference Material OxL63, 23 October 2007. Page 1 of 6.

161 Neilson Street, Auckland, New Zealand Email: [email protected]

Tel: +64 9 634 7696 Fax: +64 9 634 6896 Website: www.rocklabs.com Certificate of Analysis







Malcolm Smith Reference Materials Ltd


North Shore City 0632

NEW ZEALAND


Telephone: +64 9 444 3534

Date of Certification: 23 October 2007











P O Box 18 142

Auckland

NEW ZEALAND



Telephone: +64 9 634 7696









%

SiO2 62.28

Al2O3 17.57

Na2O 6.85

K2O 3.36

CaO 2.40

MgO 2.46

TiO2 0.70

MnO 0.05

P2O5 0.23

Fe2O3 3.74

L O I 0.31



monitoring purposes.





conditions.










An independent laboratory carried out all gold analyses by fire assay of 30 g portions,



Homogeneity Assessment After Packaging

The contents of six randomly selected jars were compacted by vibration (to simulate






produced a coefficient of variation of 0.9 %.






were given. All laboratories used fire assay for the gold analysis.







of these statistical analyses, three sets of results were excluded for the purpose of




X ± ts/√n






submitted results are listed on page 5.



Gold (ppm)


5.25 5.64 5.445

5.561 5.645 5.6030

5.42 5.84 5.630

5.62 5.76 5.690

5.73 5.80 5.765

5.74 5.79 5.765

5.81 5.80 5.805

5.825 5.795 5.8100

5.73 5.91 5.820

5.84 5.82 5.830

5.956 5.735 5.8455

5.850 5.880 5.8650

5.896 5.853 5.8745

5.85 5.90 5.875

5.846 5.949 5.8975

5.849 6.025 5.9370

5.97 5.92 5.945

5.90 5.99 5.945

5.967 5.933 5.9500

5.94 5.97 5.955

5.95 5.96 5.955

6.034 5.897 5.9655

5.985 5.959 5.9720

5.94 6.04 5.990

6.00 6.00 6.000

5.97 6.04 6.005

6.034 5.983 6.0085

6.015 6.105 6.0600



Coefficient of variation = 2.4 %


Note: this standard deviation should not be used as

a basis to set control limits when plotting results

from an individual laboratory.

Statistical analysis of both homogeneity and consensus test results has been carried

out by independent statistician, Tim Ball.



Australia ALS Chemex, Perth

Amdel Ltd, Adelaide

Amdel Laboratories Ltd, Perth

Amdel Laboratories Ltd, Kalgoorlie

Genalysis Laboratory Services Pty Ltd, Perth

SGS Welshpool Minerals, Perth

SGS Townsville Minerals, Townsville

Standard and Reference Laboratories, Perth

Ultra Trace Analytical Laboratories, Perth

Canada ALS Chemex, British Columbia

ALS Chemex, Quebec

Assayers Canada, British Columbia

Bourlamaque Assay Laboratories Ltd, Quebec

International Plasma Labs Ltd, British Columbia

Loring Laboratories, Alberta

SGS Minerals Services, Ontario

TSL Laboratories Inc, Saskatchewan

Chile ACME Analytical Laboratories Ltda

Kyrgyzstan Alex Stewart Assay and Environmental Laboratories Ltd

New Zealand SGS Minerals, Waihi

Peru Minera Yanacocha SRL – Newmont

Russia Irgiredmet, Irkutsk

Russian Academy of Science, Karelia

South Africa Anglo Research

MINTEK: Analytical Services Division

SGS Lakefield Research Africa

United States of America ALS Chemex, Nevada

Barrick Goldstrike Mines Inc, Nevada


Newmont Mining Corporation, Lone Tree Laboratory

Newmont Mining Corporation, Twin Creeks Laboratory

























this more simply for themselves, we can provide a free Excel template that will produce

sensible graphs, with intelligently chosen limits, from the customer’s own data.

Legal Notice:


and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and

Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the

reference material.

References:





Certificate of Analysis, ROCKLABS Reference Material OxL78, 19 June 2009. Page 1 of 6.








Malcolm Smith Reference Materials Ltd


North Shore City 0632

NEW ZEALAND


Telephone: +64 9 444 3534

Date of Certification: 19 June 2009











P O Box 18 142

Auckland 1743

NEW ZEALAND



Telephone: +64 9 634 7696









%

SiO2 59.34

Al2O3 17.58

Na2O 5.16

K2O 4.96

CaO 3.51

MgO 2.94

TiO2 0.92

MnO 0.07

P2O5 0.24

Fe2O3 4.70

L O I 0.56



monitoring purposes.





conditions.









An independent laboratory carried out all gold analyses by fire assay of 30 g portions,




Homogeneity Assessment continued:

The contents of five randomly selected jars were compacted by vibration (to simulate






produced a relative standard deviation of 1.3 %.






were given. All laboratories used fire assay for the gold analysis, with some using an

instrument finish and some a gravimetric finish.







of these statistical analyses, six sets of results were excluded for the purpose of




X ± ts/√n







individual laboratory averages. A code also indicates the method used by the

laboratory. The code starts with the sample weight used (where this is known) and

finishes with either the instrument used (eg AAS or ICP-OES) or gravimetric finish

(indicated by “grav”). Statistical analysis was carried out separately on two groups of

samples – those analysed with an instrument finish and those completed by

gravimetry. There was no significant difference in the calculated gold average for

each group. This applied with outliers included as well as with outliers excluded,

therefore the assigned value was calculated from the combined sets of results.





Method Sample 1 Sample 2 Average

30gfa/grav 5.63 5.54 5.585

50gfa/ICP 5.55 5.65 5.600

30gfa/AAS 5.65 5.69 5.670

50gfa/AAS 5.65 5.70 5.675

fa/AAS 5.664 5.703 5.684

20gfa/AAS 5.73 5.66 5.695

15gfa/grav 5.66 5.73 5.695

30gfa/AAS 5.70 5.75 5.725

fa/grav 5.84 5.72 5.780

30gfa/AAS 5.774 5.840 5.807

30gfa/ICP-ES 5.86 5.80 5.830

50gfa/AAS 5.86 5.80 5.830

30gfa/AAS 5.85 5.81 5.830

50gfa/AAS 5.86 5.83 5.845

fa/AAS 5.820 5.875 5.848

30gfa/AAS 5.83 5.90 5.865

fa/grav 5.884 5.884 5.884

30gfa/AAS 5.84 5.94 5.890

30gfa/grav 5.88 5.92 5.900

30gfa/AAS 5.900 5.900 5.900

10gfa/AAS 5.87 5.94 5.905

30gfa/grav 5.95 5.88 5.915

fa/grav 5.874 5.957 5.916

30gfa/AAS 5.984 5.969 5.977

30gfa/grav 5.99 5.97 5.980

15gfa/AAS 5.983 5.983 5.983

30gfa/AAS 6.03 5.96 5.995

30gfa/grav 6.039 5.957 5.998

30gfa/AAS 6.01 6.05 6.030

50gfa/AAS 6.050 6.045 6.048

fa/grav 6.093 6.057 6.075

30gfa/AAS 6.09 6.12 6.105

30gfa/AAS 6.17 6.15 6.160

40gfa/ICP-OES 6.140 6.200 6.170



Relative standard deviation = 2.6 %


Gold (ppm)

Note: this standard deviation should not be used as a basis to set control limits

when plotting results from an individual laboratory.



Australia ALS Chemex, Kalgoorlie

ALS Chemex, Perth

Amdel Ltd, Adelaide

Amdel Ltd, Kalgoorlie

Genalysis Laboratory Services Pty Ltd, Perth

SGS Australia Pty Ltd, Perth

SGS Australia Pty Ltd, Townsville

Standard and Reference Laboratories, Perth

Ultra Trace Pty Ltd, Perth

Burkina Faso ALS Chemex, Ouagadougou

Canada Accurassay Laboratories, Thunder Bay

Acme Analytical Laboratories Ltd, Vancouver

ALS Chemex, Val d’Or

ALS Chemex, Vancouver

Assayers Canada, Vancouver

Bourlamaque Assay Laboratories Ltd, Val d’Or

International Plasma Labs Ltd, Richmond

Loring Laboratories Ltd, Calgary

SGS Mineral Services, Lakefield

Techni-Lab S.G.B. Abitibi Inc, Quebec


Chile Acme Analytical Laboratories Ltd, Santiago

Kyrgyzstan Alex Stewart Assay and Environmental Laboratories Ltd, Kara-Balta

Mali ALS Chemex, Bamako

New Zealand Amdel NZ Ltd, Macraes, Otago

Amdel Ltd, Reefton

SGS Minerals, Waihi

Peru ALS Chemex, Lima


Inspectorate Services Peru S.A.C., Callao

Russia Irgiredmet JSC, Analytical Centre, Irkutsk

South Africa AB Analytical Laboratory Services, Boksburg

Anglo Research, Johannesburg


SGS South Africa (Pty) Ltd, Barberton

SGS South Africa (Pty) Ltd, Southdale

United States of America ALS Chemex, Reno

Barrick Goldstrike Mines Inc, Carlin


Newmont Mining Corporation, Lone Tree Laboratory

























this more simply for themselves, we can provide a free Excel template that will produce

sensible graphs, with intelligently chosen limits, from the customer’s own data.

Legal Notice:


and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and

Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the

reference material.

References:





Certificate of Analysis, ROCKLABS Reference Material OxL118. 26 November 2013. Page 1 of 6



www.rocklabs.com








within the following range: 336 813– 340 182.

Prepared and Certified By: Brett Coombridge, M.Phil. Chemistry


P.O. Box 316056

Wairau Valley Post Centre

Auckland 0760

NEW ZEALAND


Telephone: +64 9 444 3534

Date of Certification: 26 November 2013










Supplier of Reference Material: ROCKLABS

P O Box 18 142

Glen Innes

Auckland 1743

NEW ZEALAND



http://www.rocklabs.com/









%

SiO2 59.24

Al2O3 16.73

Na2O 4.33

K2O 6.40

CaO 3.22

MgO 3.24

TiO2 0.88

MnO 0.06

P2O5 0.23

Fe2O3 4.77

L O I 0.19




Stability: The container (jar or sachet) should not be heated to

temperatures higher than 50 °C. The reference material is

stable, with weight changes of less than 0.5 % at extremes of

naturally occurring temperature and humidity conditions.


with finely pulverized and screened gold-containing minerals.

Once the powders were uniformly mixed the composite was

placed into 3370 wide-mouthed jars, each bearing a unique

number. 60 jars were randomly selected from the packaging

run and material from these jars was used for both

homogeneity and consensus testing.


Sampling (described below) was performed by Rocklabs Reference Materials and an

independent laboratory carried out gold analysis of the samples by fire assay of 30 g

portions, using a gravimetric finish. Steps were taken to minimize laboratory method

variation to better detect any variation in the candidate reference material.


Homogeneity: A sample was removed from the top of each of the 60 jars randomly

selected from the 3370 jars in the batch. The results of analysis of the 60 samples

(randomly ordered then consecutively numbered before being sent to the laboratory)

produced a relative standard deviation of 1.0%.

Settling: The contents of 6 randomly selected jars were compacted by vibration (to

simulate the effect of freighting) and 5 samples were removed successively from top

to bottom from each jar. In addition, 5 samples were removed and tested from the

last jar in the series. No top to bottom gradation in the gold values was observed

neither was there a significant difference between the last jar and the other jars.




testing. The sub-samples were drawn from 60 randomly selected jars and each

laboratory received samples from two different jars.

Participating laboratories analysed the samples by fire assay followed by either

gravimetric or instrument finish (AAS or ICP). Indicative concentration ranges were

provided. Some laboratories analysed the samples twice using both methods. In this

situation both sets of results were presented separately, and included in the statistical

analysis. The amount of sample used in the analyses varied between laboratories

(range 15 - 50g).


As some laboratories returned results for two different methods, 58 sets of gold

results were returned from 54 laboratories. Statistical analysis to identify outliers was

carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994.

Assessment of each laboratory’s performance was carried out on the basis of z-scores,

partly based on the concept described in ISO/IEC Guide 43-1. Details of the criteria

used in these examinations are available on request. As a result of these statistical

analyses, 4 sets of results were excluded for the purpose of assigning a gold

concentration value to this reference material. A recommended value was thus

calculated from the average of the remaining n = 54 sets of replicate results. The

95% confidence interval was estimated using the formula:-

X ts/√n












Note: Neither the Standard deviation nor the Confidence interval should be

used as a basis to set control limits when plotting individual laboratory results.

See notes under "Instructions and Recommendations for Use" (pg 6)

Sample 1 Sample 2 Set Average5.32 5.68 5.5

5.52 5.54 5.53

5.571 5.55 5.5585

5.61 5.54 5.575

5.750 5.448 5.599

5.69 5.52 5.605

5.480 5.785 5.6325

5.62 5.67 5.645

5.49 5.83 5.66

5.725 5.612 5.6685

5.7 5.7 5.7

5.705 5.715 5.71

5.72 5.76 5.74

5.750 5.750 5.75

5.685 5.820 5.7525

5.80 5.71 5.755

5.729 5.782 5.7555

5.69 5.83 5.76

5.758 5.772 5.765

5.80 5.76 5.78

5.890 5.760 5.825

5.8 5.85 5.83

5.93 5.74 5.835

5.844 5.830 5.837

5.865 5.810 5.8375

5.8 5.9 5.84

5.814 5.868 5.841

5.840 5.855 5.8475

5.970 5.735 5.8525

5.84 5.87 5.855

5.890 5.830 5.86

5.861 5.863 5.862

5.78 5.96 5.87

5.88 5.86 5.87

5.89 5.86 5.875

5.78 5.98 5.88

5.871 5.906 5.8885

5.90 5.89 5.895

5.86 5.97 5.915

5.91 5.93 5.92

5.91 5.94 5.925

5.92 5.95 5.935

5.99 5.89 5.94

5.95 5.93 5.94

5.94 5.94 5.94

5.94 5.96 5.95

5.97 5.98 5.975

6.02 5.95 5.985

5.99 5.98 5.985

6.02 5.97 5.995

6.00 6.10 6.05

6.093 6.137 6.115

6.11 6.14 6.125

6.15 6.19 6.17


Standard deviation of 54 sets = 0.149 ppmRelative standard deviation = 2.6 %95% Confidence interval for average: = +/- 0.041 ppm

Gold (ppm)



Australia ALS Minerals, Burnie

ALS Minerals, Kalgoorlie


ALS Minerals, Perth


Bureau Veritas Amdel, Adelaide

Bureau Veritas Amdel, Kalgoorlie

Intertek Genalysis Laboratory Services, Perth


SEMAFO Burkina Faso S.A.


ALS Minerals, Val-d’Or


Bourlamaque, Quebec


SGS Minerals Services, Lakefield, Ontario


Techni-Lab S.G.B. Abitibi Inc/Actlabs, Val d’Or

Techni-Lab S.G.B. Abitibi Inc/Actlabs, Ste-Germaine-Boule




Ghana ALS Minerals, Kumasi

SGS Performance Lab, Obuasi AngloGold

Ireland ALS Minerals, Loughrea


Laos ALS Geochemistry, Vientiane


Mongolia ALS Minerals, Ulaanbaatar

Namibia Bureau Veritas- Mineral Laboratories, Swakopmund

New Zealand SGS New Zealand Ltd, Otago

SGS New Zealand Ltd, Reefton

SGS New Zealand Ltd, Waihi




Romania ALS Minerals, Rosia Montana


South Africa AB Analytical Laboratory Services, Boksburg

Acme, Inspectorate M & M, Rustenburg

ALS Minerals, Edenvale

SibanyeGold, Driefontein Operations

Performance Laboratories, Barberton


Performance Laboratories, Allanridge

Turkey Acme Analitik Laboratuar Hizmetleri Ltd, Sirketi

ALS Minerals, Izmir


Barrick Goldstrike – Met Services, Nevada

Inspectorate, Sparks

Newmont Mining Corporation, Carlin

Newmont Mining Corporation, Lone Tree

Newmont Mining Corporation, Twin Creeks

Zimbabwe Performance Laboratories, Ruwa



Weigh out quantity usually used for analysis, and analyse for total gold by normal
























Legal Notice:


and attention. However ROCKLABS Ltd, Scott Technology Ltd and Tim Ball Ltd accept


References:


contact Brett Coombridge.


Brett Coombridge (M.Phil. Chemistry) Tim Ball BSc (Hons)

Certificate of Analysis, ROCKLABS Reference Material OxL51, 13 March 2006. Page 1 of 6.





The above values apply only to product in jars or sachets which have an identification number within the following range: 113 965 – 115 300.

Prepared and Certified By: Malcolm Smith BSc, FNZIC Malcolm Smith Reference Materials Ltd 40 Oakford Park Crescent, Greenhithe, Auckland 1311 NEW ZEALAND


Telephone: +64 9 444 3534

Fax: +64 9 444 7739

Date of Certification: 13 March 2006


Available Packaging: This reference material has been packed in wide-mouthed jars that contain 2.5 kg of product. The contents of some jars may be subsequently repacked into sealed polyethylene sachets.

Origin of Reference Material: Feldspars with minor quantities of finely divided gold-containing minerals that have been screened to ensure there is no gold nugget effect.

Supplier of Reference Material: ROCKLABS Ltd P O Box 18 142 Auckland NEW ZEALAND

Email: [email protected] Website: www.rocklabs.com Telephone: +64 9 634 7696


Description: The component minerals have been well mixed and a homogeneity test carried out after the entire batch was packaged into wide-mouthed jars to ascertain that the gold is evenly distributed throughout the reference material. There is no soil component. The product contains crystalline quartz and therefore dust from it should not be inhaled.


(Uncertified Values) %

SiO2 67.26

Al2O3 19.11

Na2O 8.54

K2O 3.62

CaO 0.21

MgO 0.17

TiO2 0.03

MnO 0.00

P2O5 0.09

Fe2O3 0.53

L O I 0.34

Intended Use: This reference material is designed to be included with every batch of samples analysed and the results plotted for quality monitoring purposes.

Stability: The container (jar or sachet) and its contents should not be heated to temperatures higher than 50 °C. The reference material is stable, with weight changes of less than 0.5 % at extremes of naturally occurring temperature and humidity conditions.

Method of Preparation: Pulverized feldspar minerals were blended with finely pulverized and screened, gold-containing minerals. Once the powders were uniformly mixed the composite was placed into 1336 wide-mouthed jars, each bearing a unique number. 40 jars were randomly selected from the packaging run and material from these jars was used for both homogeneity and consensus testing.



An independent laboratory carried out all gold analyses by fire assay of 30 g portions, using a gravimetric finish with a balance capable of reading to one microgram. Steps were taken to minimize laboratory method variation in order to better detect any variation in the candidate reference material. Homogeneity Assessment After Packaging

The contents of five randomly selected jars were compacted by vibration (to simulate the effect of freighting) and five samples removed successively from top to bottom from each jar. In addition, five samples were removed from the last jar in the series. A sample was removed from the top of each of the 40 jars randomly selected from the 1336 jars in the batch. The results of analysis of the 70 samples (randomly ordered and then consecutively numbered before being sent to the laboratory) produced a coefficient of variation of 0.5 %.


Once homogeneity had been established, two sub-samples were submitted to a number of well-recognized laboratories in order to assign a gold value by consensus testing. The sub-samples were drawn from the 40 randomly selected jars and each laboratory received samples from two different jars. Indicative concentration ranges were given. All laboratories used fire assay for the gold analysis.


Results for gold were returned from 29 laboratories. Statistical analysis to identify outliers was carried out using the principles detailed in sections 7.3.2 – 7.3.4, ISO 5725-2: 1994. Assessment of each laboratory’s performance was carried out on the basis of z-scores, partly based on the concept described in ISO/IEC Guide 43-1. Details of the criteria used in these examinations are available on request. As a result of these statistical analyses, four sets of results were excluded for the purpose of assigning a gold concentration value to this reference material. A recommended value was thus calculated from the average of the remaining n = 25 sets of replicate results. The 95 % confidence interval was estimated using the formula:-

X ± ts/√n (where X is the estimated average, s is the estimated standard deviation of the laboratory averages, and t is the 0.025 tail-value from Student’s t-distribution with n-1 degrees of freedom). The recommended value is provided at the beginning of the certificate in µg/g (ppm) units. A summary of the results used to calculate the recommended value is listed on page 4 and the names of the laboratories that submitted results are listed on page 5.



Statistical analysis of both homogeneity and consensus test results has been carried out by independent statistician, Tim Ball.

Gold (ppm)


5.562 5.685 5.6245.53 5.77 5.6505.69 5.63 5.660

5.700 5.665 5.6835.763 5.727 5.7455.78 5.80 5.790

5.830 5.773 5.8025.88 5.74 5.810

5.885 5.765 5.8255.78 5.87 5.8255.83 5.83 5.8295.83 5.88 5.8535.85 5.87 5.8585.89 5.83 5.860

5.865 5.860 5.8635.829 5.907 5.8685.81 5.96 5.8855.88 5.94 5.905

5.915 5.900 5.9085.94 5.88 5.910

5.945 5.895 5.9205.95 5.94 5.9456.02 6.01 6.0156.06 6.09 6.075

6.153 6.134 6.144

Average of 25 sets = 5.850 ppmStandard deviation of 25 sets = 0.123 ppm

Coefficient of variation = 2.1 %95% Confidence interval for average = 0.051 ppm



Australia ALS Chemex, Perth Amdel Ltd, Adelaide Amdel Laboratories Ltd, Perth

Amdel Ltd, Kalgoorlie Genalysis Laboratory Services Pty Ltd, Perth SGS Australia Pty Ltd, Perth SGS Australia Pty Ltd, Townsville Standard and Reference Laboratories, Perth Ultra Trace Analytical Laboratories, Perth

Canada Accurassay Laboratories, Ontario Acme Analytical Laboratories Ltd, British Columbia ALS Chemex, British Columbia ALS Chemex, Quebec Assayers Canada, British Columbia Bourlamaque Assay Laboratories Ltd, Quebec International Plasma Labs Ltd, British Columbia Loring Laboratories Ltd, Alberta TSL Laboratories Inc, Saskatchewan

Kyrgyzstan Alex Stewart Assay and Environmental Laboratories Ltd

New Zealand Amdel Ltd, Otago SGS New Zealand Ltd, Waihi

Russia Irgiredmet, Irkutsk Norilsk Nickel, Trans-Polar Division Russian Academy of Science, Karelia

South Africa MINTEK, Analytical Science Division SGS Lakefield Research Africa (Pty) Ltd

United States of America ALS Chemex, Nevada Barrick Goldstrike Mines Inc, Nevada Newmont Mining Corporation, Nevada



Weigh out quantity usually used for analysis and analyze for total gold by normal procedure. Homogeneity testing has shown that consistent results are obtainable for gold when 30g portions are taken for analysis.

We quote a 95% confidence interval for our estimate of the declared value. This confidence interval reflects our uncertainty in estimating the true value for the gold content of the reference material. The interval is chosen such that, if the same procedure as used here to estimate the declared value were used again and again, then 95% of the trials would give intervals that contained the true value. It is a reflection of how precise the trial has been in estimating the declared value. It does not reflect the variability any particular laboratory will experience in its own repetitive testing.

Some users in the past have misinterpreted this confidence interval as a guide as to how different an individual test result should be from the declared value. Some mistakenly use this interval to set limits for control charts on their own routine test results using the reference material. Such use inevitably leads to many apparent out-of-control points, leading to doubts about the laboratory’s testing, or of the reference material itself. A much better way of determining the laboratory performance for testing the reference material is to accumulate a history of the test results obtained, and plot them on a control chart. The appropriate centre line and control limits for this chart should be based on the average level and variability exhibited in the laboratory’s own data. This chart will provide a clear picture of the long-term stability or otherwise of the laboratory testing process, providing good clues as to the causes of any problems. To help our customers do this more simply for themselves, we can provide a free Excel template that will produce sensible graphs, with intelligently chosen limits, from the customer’s own data.

Legal Notice:

This certificate and the reference material described in it have been prepared with due care and attention. However ROCKLABS Ltd, Malcolm Smith Reference Materials Ltd and Tim Ball Ltd accept no liability for any decisions or actions taken following the use of the reference material.

References:

For further information on the preparation and validation of this reference material please contact Malcolm Smith.



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