Applied MineralogistThe bulletin of the pplied ineralogy roupA M G

September 2017Volume 2, Number 3

Edited by: George Guice Andrew Dobrzanski

Web: http://www.minersoc.org/amg.htmlTwitter: @amg_minEmail: amgminsoc@gmail.com

From the AMG committeeDear Applied Mineralogist readers, welcome to the fifth bulletin from the AMG. It is our pleasure to share with you reports from our PhD student reps and bursary awardees. It's also our privilege to include a special feature about diffusion in diamonds, courtesy of Ben Harte and John Craven at the University of Edinburgh. We hope you enjoy this issue – until Christmas, adieu.

#AppliedMineralogy @ArcheanGeo

"The Blue Picasso". Zoned #diamond in CL for #ThinSectionThursday. Coesite/omphacite inclusions in black. Tim Ivanic (@ArcheanGeo)

To see more of the “blue picasso”, see our special feature, written by Ben Harte & John Craven.

AMG bursary report: European Rare Earth Resources Conferene 2017 Eva Marquis

ndThanks to the AMG student bursary, I attended the 2

European Rare Earth Resources conference. The

conference took place in May on Santorini and was

organised by the EURARE and EREAN projects. The

conference covered a range of REE-related topics,

from policy to production as well as magnet recycling

and, of course, geology and mineralogy. My

presentation was in the “REE resources beyond

E u r o p e ” s e s s i o n a n d i n t r o d u c e d t h e

Ambohimirahavavy alkal ine complex (NW

Madagascar) that has an associated ion adsorption-

type REE deposit. The talk introduced the geology of

the complex, before discussing the potential effects of

hydrothermal alteration on developing mineral

assemblages amenable to breaking down and

releasing REE during chemical weathering. The

presentation went well, with a good discussion at the

end of the session. I am one of a number of students and

researchers working on the SoSRARE project, and it

was the first conference where all the strands of this

project have been in attendance – it was great to see how

the work on this project is fitting onto the wider topic of

sustainable REE supply in Europe and globally.

The conference finished with a fantastic fieldtrip to the

Akrotiri ruins, a settlement buried in ash and pumice

from the 1672 BC eruption, followed by a boat trip to

Nea Kameni to investigate the lava flows of this newest

volcanic edifice. It was a great day for all the geologists

on board, finding beautiful yellow sulphate minerals

deposited around old fumaroles (see picture), as well

as spotting the various lava tubes and flows of the old

shield volcano in the cliffs.

Sulphate mineral around fumaroles, Nea Kameni.

Green Energy - Opportunities and Challenges to Applied Mineral Research Andrew Dobrzanski

Solar power, once derided as expensive and unreliable, has received a boost in recent years due to improved photovoltaic (PV) technology and a drop in the price per PV unit cost. This price drop has been due to increased Chinese PV manufacturing with units allegedly being sold at a loss to dominate the market. The influx of cheap PV has reduced costs and increased installed PV capacity by 76 Gw in 2016

(article continues on page 3)

In this issue:

Ÿ From the AMG committee

Ÿ #AppliedMineralogy @ArcheanGeo

Ÿ AMG bursary report: Rare Earth Resources

Ÿ Special feature: Carbon isotope mapping and diffusion in diamond

Ÿ Green energy: opportunities and challenges

Ÿ Coffee room small-talk: mineral application factsŸ Calendar Ÿ About us

AMGAMG

Background and Objectives

The carbon isotope composition of

natural diamonds is widely used as

an indicator of their conditions of

formation and the source of the

f l u i d / m e l t f ro m wh i c h t h ey

precipitate in the Earth's mantle [1, 2].

Given that estimates of the ages of

natural diamonds are commonly

more than 1000 million years [3], and

that mantle residence temperatures

are widely expected to be between

1200-1400ºC, the possibility arises

that the initial carbon isotope

composition of the diamond may be

modified by diffusion while at depth

in the mantle [4].

P rev i o u s l y, i o n m i c ro p ro b e

determinations of carbon isotope

ratio in diamonds have been done by

a few analyses at selected points

across the crystals [4, 5]. These point

analyses are then compared with the

growth zones in the diamond

revealed by cathodoluminescence

(CL). Studies of different diamonds

show both the absence and presence

of variations in carbon isotopes in

conjunction with growth zones [4, 6],

but the detail of isotope ratio

variation in relation to growth zone

structure has not been determined.

Clearly, the extent of detailed

correspondence of carbon isotope

compositions with the original

growth zone structure across a whole

crystal would provide a test of

wh e t h e r ex t e n s ive d i f f u s ive

m o d i f i c a t i o n h a d o c c u r re d

subsequent to crystal growth. The

purpose of the measurements

reported here was to map carbon

isotope compositions in sufficient

d e t a i l t o e x a m i n e t h i s

correspondence.

MethodT h e C a m e c a i m s 1 2 7 0 i o n microprobe enables rapid, high precision analyses to be performed automatically over long periods of time, meaning that it is now possible to map minerals for minor variations in isotopic ratios.

The diamond crystal selected for measurement was mounted in indium between two standards of known isotopic composition. An array of ion probe pits were used to create the

13contour plots of δ C.

Point determinations on the sample

were made at 100µm intervals along l i n e t r a n s e c t s , w h i c h w e re

themselves 100 µm apart. This made a grid of 26 lines with up to 24 points per line. Five measurements were made on the standard crystals at the start and end of each line – thus enabling calibration of the sample measurements for each line against 10 standard measurements.

ResultsThe diamond selected for study is part of the collection from Guaniamo, Venezuela, investigated by Schulze et al. [7], and is notable for its complex CL pattern, which has led to it being referred to as the 'Picasso' diamond (Fig. 1). It figured in Nature (volume 423, page 24) and on the cover of the

t h8 I n t e r n a t i o n a l K i m b e r l i t e Conference Hawthorne volume (2004). The CL image is shown opposite.

The collected carbon isotope data,

forming a grid of points at 100 µm

intervals, have been contoured to

yield a map of carbon isotope

variation across the whole crystal

(Fig. 2; Fig. 3).

Discussion

As may be seen the growth pattern of t h e C L i m a g e i s m a t c h e d exceptionally closely by the carbon isotope map. This matching includes details of the four corners of the inner areas as well as the overall growth patterns. There is no evidence of disturbance of carbon isotope compositions subsequent to growth by diffusive equilibration across the growth zones. This result strongly

13supports the view that the δ C values measured on natural diamonds are

1 3direct ly re la ted to the δ C composition of the mantle fluid reservoir from which the diamond grew.

Fig. 1: “picasso” diamond approx.

240 µm diameter.

Fig. 2: contour plot showing the range 13

in δ C from -9.8 (yellow) to -17.8 (red).

Fig. 3: 3D construction of the 13

contoured δ C.

References[1] Galimov, E.M. Geochim. Cosmochim. Acta, 55 (1991) 1697–1708. [2] Kirkley, M.B., Gurney, J.J., Otter, M.L., Hill, S.J. and Daniel, L.R. Appl. Geochem., 6 (1991) 477-494. [3] Harris, J.W. In Nixon, P.H.(ed.) Mantle Xenoliths, Wiley & Sons, (1987) 478-500. [4] Harte, B., Fitzsimons, I.C.W., Harris, J.W. and Otter, M.L. Min. Mag. 63 (1999) 829-856.[5] Hauri E.H., Wang J., Pearson D.G., Bulanova G.P. Chem Geology 185 (2002) 149-163. [6] Fitzsimons ICW, Harte B, Chinn IJ, Gurney JJ, Taylor WR Mineral Magazine 63 (1999) 857-878. [7] Schulze, D.J., Harte, B., Valley, J.W., Brenans, J.M., & Channer, D.M.De R. Nature, 423 (2003) 68-70.

Special Feature: Carbon Isotope Mapping and Diffusion in DiamondBen Harte and John Craven (School of Geoscience, Grant Institute, University of Edinburgh)

Interested in joining the Mineralogical Society and Applied Mineralogy Group? Go to: for membership details.http://www.minersoc.org/

Coffee break small-talk: mineral application facts

Ÿ 18 g of diamond has the same combustion energy as a Mars bar (other chocolate bars are available).

Ÿ Deerite, howieite and zussmanite can all be found in blueschist-facies meta-ironstone in Laytonville, California.

Ÿ Your smartphone contains roughly 75 % of the elements in the periodic table. For example:

Screen: Electronics:

AMGAMG

SEP ‘1730

JUL ‘1830 - 6

About UsFounded in 1963 by Norman F.M. Henry, the AMG is a special interest group of the Mineralogical Society of Great Britain and Ireland. We encourage and promote the study and research of mineralogy applied to ores and related industrial mineral materials. This encompasses: ore microscopy, fluid inclusions, nuclear minerals, coals, refractories, slags, ceramics, building materials, nuclear waste disposal, carbon capture and storage, down-hole borehole alteration, and mineral-related health hazards.

SEP ‘1725 - 27

JUL ‘18 10 - 13

Calendar

AMG bursary deadline. See:

http://www.minersoc.org/amg.html

Fermor Meeting, London, UK.

https://www.geolsoc.org.uk/fermor17

Brian Lovell Meeting: Mining for the future. https://www.geolsoc.org.uk/Lovell17

MDSG (Mineral Deposit Studies Group) conference, Brighton, UK

Platinum Symposium, Mokopane, South Africa.

Granulites & granulites, Ullapool, UK

alone. Globally, total PV capacity installed is 305 Gw (up from 50 Gw in 2010). The growth of solar is changing the energy market. In 2016, 2% of new jobs in the US were due to the solar industry. India aims to produce 175 Gw from renewables by 2022, while solar panels are used by communities around artisanal mines, reducing the need for state installed power infrastructure in remote areas. A desire for improved PV materials is increasing research opportunities into engineered synthetic minerals, such as perovskites.

As PV demand grows, so does the demand for raw

materials to manufacture them. PV panels incorporate

Nb, Cd, Mo and Ga along with critical elements Li, In

and Te. The challenge of the six-fold increase in global

PV capacity is managing the pressure on the supply of

these elements to the market. There is a secure supply

for some of these elements. For example, Mo is

currently in oversupply and Nb sources in Brazil are

stable, but projections suggest that Li and In will

remain 'fairly balanced', depending on new supplies

coming online. However, elements such as Cd and Ga,

which are produced as a co-products of metal refining

may experience a supply shortage if there is a

downturn in primary metal mining (i.e. Zn, Al).

The boom in renewable energy has also created other

mineral supply issues. April 2017 saw the first time

since the industrial revolution that British power

generation achieved a 'coal free' day. While this is a

significant achievement, the move away from coal has

begun a separate critical resource issue. The UK

Quality Ash Association (QAA) has for some time been

warning that the UK supply of Pulverised Fuel Ash (PFA

or “fly ash”) is at risk. PFA is used in fillers, cements and

grouts, in applications from shallow mine-working

remediation to highway construction and block

making; and as coal power in the UK is phased out we

will need to solve new challenges surrounding the

supply of these waste products to our construction

industries.

Green Energy Case Study: Te and Se Katie McFall

As mentioned in the above article, elements mined as

co-products, such as Te and Se, present both

challenges and opportunities. If extracted efficiently,

producing critical metals as co-products is potentially

a more environmentally friendly and sustainable way

of ensuring supply. However, they are subject to

fluctuations in base metal markets, which may not

reflect the needs of specialist technologies. Moreover,

extracting these co-products can be expensive and

technically challenging. Te and Se, for example, are

produced as by-products of Cu mining and are

currently extracted from anode slimes at copper

refineries after the processing of ore from porphyry

copper deposits and volcanogenic massive sulphide

(VMS) deposits. Although whole-rock assay data

reveals that Te and Se are present in Cu deposits, little

is known about the mineralogical and spatial controls

within deposits. This inhibits efficient processing,

meaning that some of the resource is being lost. Te

minerals are also found in many gold deposits, such as

Cripple Creek (USA) and Perama Hill (Greece). These

are not, however, currently being mined for Te due to a

lack of efficient extraction techniques. Research into

new processing methods is ongoing, but it requires a

clearer understanding of the mineralogy and

enrichment mechanisms of these elements.

InIndium

OOxygen

SnTin

AlAluminium

SiSilicon

KPotassium

YYttrium

LaLanthanum

TbTerbium

PrPraesodymium

DyDysprosium

EuEuropium

GdGadolinium

CuCopper

OOxygen

SnTin

PPhosphorus

SiSilicon

AgSilver

AuGold

TaTantalum

TbTerbium

PrPraesodymium

DyDysprosium

NdNeodymium

GdGadolinium

SbAntimony

NiNickel

PbLead

JAN ‘183 - 5

NOV ‘1723 - 24