PLACER EXAMINATION TECHNIQUES SUCTION DREDGE SAMPLING ISSUES Sample by Dredging Hand tools will not give representative sample Whose equipment to use Who dredges Location of samples Amount of time SAMPLING EQUIPMENT Their dredge or yours Is it in good running condition? Is it in good running condition? Is the operator agreeable? Is the operator agreeable? Is the dredge an appropriate size? Is the dredge an appropriate size? Do you have access to a dredge? Do you have access to a dredge? Is recovery system better? Is recovery system better? Is dredge portable? Is dredge portable? Sampling Equipment cont. Hand Tools pry bars (various sizes), shovel or rake pry bars (various sizes), shovel or rake Buckets and large wash tubs Pans, screens, and grizzlies Plastic bags, vials (glass and plastic) Brush Sampling Equipment cont. Personal equipment Wet suit, knee pads, weight belt, mask, snorkel, gloves, shoes Wet suit, knee pads, weight belt, mask, snorkel, gloves, shoes Hooka setup Waterproof permanent markers Waterproof notebooks, pencils State dredging permit (if required) DREDGE OPERATOR Determining the Operator The mineral examiner must be competent and experience to operate dredge Operator objections Mineral examiners competence and experience Mineral examiners competence and experience Knowledge of deposit Knowledge of deposit Ability to use operators equipment Ability to use operators equipment Mineral examiner should be familiar and comfortable with operator Sample Security for Claimant Dredging Inspect hole or site before dredging At least one mineral examiner in the water next to operator at all times Only mineral examiners tending sluice, cleaning sluice or processing sample SELECTION OF SAMPLE SITE Choose wisely one sample takes one day One sample per ten-acre parcel, minimum One in vicinity of discovery site Site Selection cont. Sites representative of stream morphology Space out along length of stream Get input from claimant claimant selected sites are preferable Take into consideration past dredging Access to stream Logistics of getting dredge in and out Consider during mapping Consider during mapping SAMPLE SITE PREPARATION Working Face Claimant may open hole to bedrock or to some other level were they recover gold Claimant may open hole to bedrock or to some other level were they recover gold Gives start on working faceGives start on working face Gives operator chance to evaluate siteGives operator chance to evaluate site Surface gravel is generally less valuableSurface gravel is generally less valuable Get estimate of time spent opening holeGet estimate of time spent opening hole Examiner Preparation Remove hand sized boulders from site Document time and people Document time and people Inspect site for possible salting Look under rocks and fan sediment Look under rocks and fan sediment Inspect dredge Run for a few minutes without carpeting or riffles Run for a few minutes without carpeting or riffles SUCTION DREDGE SAMPLING Sampling Time At least 2 hours of production time per sample Often takes about 5 hours Often takes about 5 hours Track production vs. non-production time Production time - when gravel is being processed Production time - when gravel is being processed Non-Production time refueling, rest breaks, clearing major plugs, moving boulders Non-Production time refueling, rest breaks, clearing major plugs, moving boulders Other non-production time Packing, assembling, and moving dredge and transporting supplies Packing, assembling, and moving dredge and transporting supplies Suiting up Suiting up Cleanup of sluice Cleanup of sluice Processing concentrates Processing concentrates Mineral Examiner Duties Three person crew (minimum) One mineral examiner operating nozzle One crew member in water assisting with rocks and monitoring for safety Both make mental notes of gravel and bedrock characteristics Size and angularity, percentages of rock types, clay layers, compaction, weathering, bedrock relief, structure trends, gold Size and angularity, percentages of rock types, clay layers, compaction, weathering, bedrock relief, structure trends, gold Mineral Examiner Duties cont. One crew member tends to dredge Unplugs jet and intake hose Unplugs jet and intake hose Cleans and clears cobbles from sluice Cleans and clears cobbles from sluice Breaks up clay balls Breaks up clay balls Clears spoils Clears spoils Monitors equipment operation Monitors equipment operation Keeps log of time and activity Keeps log of time and activity Protects sample security Protects sample security Mineral Examiner Duties cont. Photograph sample site before and after Underwater photos of working face and bedrock Mineral Examiner Duties cont. Examine sluice for gold during breaks Place coarse pieces of gold in vial Place coarse pieces of gold in vial At end of sampling, run straight water to clear gravel from intake hose, jet, and head box, and to clear rocks from riffles Document your mental observations in your notebook as soon as possible (usually that night) Mineral Examiner Duties cont. Measure and sketch hole, including any pertinent features Hole dimensions are needed to estimate volume and production rate Representative Sample Representative of stream morphology Attempt to reach bedrock Complete channel and stratigraphic column Work bottom but dont high grade or waste production time CONCENTRATE CLEANUP Take your time One accident or spill ruins a whole days work One accident or spill ruins a whole days work Pick visible pieces of gold and place in same vial used earlier Weighting down end of sluices aides cleanup and prevents material washing back into head box Concentrate Cleanup cont. Thoroughly clean and inspect sluice Washing all of the concentrates from the head box, riffles, and sluice box Into collection tub Cleaning Sluice cont. Carpets and Miners Moss Place in separate tub Place in separate tub Scrub with brush Scrub with brush Inspect for, and pick out embedded pieces Inspect for, and pick out embedded pieces Remove intake hose from jet and collect any gravel caught there in pan Cleaning Sluice cont. Begin screening and panning concentrates Operators typically use spiral concentrator Operators typically use spiral concentrator Place coarse gold in vial and double bag black sand concentrate Option to Amalgamation Mercury use in mine model is environmental issue Labs are getting harder to find Bowl collects as fine as 200 mesh Recovery is being tested THE END