Geochemistry Guide 2025

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Screen metallic gold analysis Analytical results can be difficult to reproduce using typical sample reduction and fire assay procedures when coarse grained metallic gold is present. To address this, the sample can be analyzed using the screened metallics sample preparation and assaying procedure. This consists of: • Screening 500g/1000g or client specified weight of the sample to a defined grain size, typically 75, 106 or 212 microns • Weighing the various fractions • Assaying the entire plus fraction • Analyzing the undersize (typically in duplicate) • Calculating and reporting of size-fraction weights, coarse and fine fraction gold content and total gold content • The finish technique may involve AAS, ICP-OES or gravimetric, depending upon concentration. Limits shown are based on instrument analysis. Gravimetric limits are higher, please contact your SGS customer service agent Note: This technique requires a minimum sample of 500g. This technique can also be used for coarse grained native metals such as platinum, palladium, silver and copper.

GOLD IN CARBON CODE GC FAA01V100 GC ACA22D100V

ELEMENT

LIMIT(S)

DESCRIPTION

Au Au Au

5 - 20,000 ppm 5 - 250,000 ppm

1 - 2 g, Fire assay, AAS finish 1 g, Ash, acid digest, AAS finish 1 - 2 g, Fire assay, gravimetric finish

≥ 7.5 ppm

GC_FAG01V

GOLD BULLION CODE GC_BUL36V

ELEMENT

LIMIT(S)

DESCRIPTION

Au

0.5 - 99.5%

100 - 500 mg, Fire assay, gravimetric finish

Silver

EXPLORATION GRADE ANALYSIS ACID DIGESTION - INSTRUMENTATION CODE

ELEMENT

LIMIT(S)

DESCRIPTION

GE_AAS22E50 GE_AAS33E50

Ag Ag Ag

0.3 - 100 ppm 0.3 - 100 ppm 0.3 - 100 ppm

2 g, 2-Acid digest, AAS finish 2 g, 3-Acid digest, AAS finish

GE_AAS42E50 2 g, 4-Acid digest, AAS finish It is recommended that mineralized samples with Ag >30 ppm are analyzed using the GO_AAS21C50 method below. Silver (Ag) can also be analyzed in many multi-element packages.

SCREENED METALLICS CODE

ELEMENT

LIMIT(S)

DESCRIPTION

ORE-GRADE ANALYSIS ACID DIGESTION - INSTRUMENTATION CODE ELEMENT

≥ 0.01 ppm

GO_FAS30K

Au Ag Au Ag Au Ag Au Ag Au Ag Au Ag

Au, Ag, screen metallics* (75/106/212), 30 g. Fire assay

≥ 10 ppm

AAS/ICP/Gray, 500g

LIMIT(S)

DESCRIPTION

≥ 0.01 ppm

GO_FAS50K

Au, Ag, screen metallics* (75/106/212), 50 g. Fire assay

≥ 10 ppm

Ag

1 - 300 ppm

0.5 g, 2-Acid digest, AAS finish

GO_AAS21C50

AAS/ICP/Gray, 500g

≥ 0.01 ppm

GO_FAS30M

Au, Ag, screen metallics* (75/106/212), 30 g. Fire assay

≥ 10 ppm

GRAVIMETRIC ANALYSIS CODE

AAS/ICP/Gray, 1000g

≥ 0.01 ppm

GO_FAS50M

Au, Ag, screen metallics* (75/106/212), 50 g. Fire assay

ELEMENT

LIMIT(S)

DESCRIPTION

≥ 10 ppm

AAS/ICP/Gray, 1000g

Au Ag Au Ag Au Ag

0.01 - 100 ppm 10 - 10,000 ppm 0.5 - 10,000 ppm 10 - 10,000 ppm 0.01 - 100 ppm 10 - 10000 ppm

30 g, Fire assay, AAS finish (Au) gravimetric finish (Ag)

GO_FAG32V

≥ 0.01 ppm

GO_FAS30V

Au, Ag, screen metallics* (75/106/212), 30 g. Fire assay

≥ 10 ppm

AAS/ICP/Gray, >1000g

30 g, Fire assay, gravimetric finish (Au, Ag)

GO_FAG33V

≥ 0.01 ppm

GO_FAS50V

Au, Ag, screen metallics* (75/106/212), 50 g. Fire assay

≥ 10 ppm AAS/ICP/Gray, >1000g * options for screen sizes available. Pt, Pd can be added. Finish technique is based on concentration.

50 g, Fire assay, AAS finish (Au), gravimetric finish (Ag)

GO_FAG52V

PROCESS CONTROL AND CONCENTRATE-GRADE ANALYSIS INSTRUMENTAL AND GRAVIMETRIC ANALYSIS CODE ELEMENT LIMIT(S)

CONTROL AND CONCENTRATE-GRADE ANALYSIS INSTRUMENTAL AND GRAVIMETRIC ANALYSIS CODE ELEMENT

DESCRIPTION

GC_FAA30V10/FAA50V10

Au Au Au

0.01 - 1,000 ppm 0.01 - 1,000 ppm

30/50 g, Fire assay, AAS finish 30 g, Fire assay, AAS finish (Au)

LIMIT(S)

DESCRIPTION

GC_FAG32V GC_FAG33V

Ag Au Ag Au Ag Ag Ag

1 - 1,000 ppm

Variable wt, 4-acid digest, AAS finish

GC_AAS43V100

≥ 0.5 ppm

30 g, Fire assay, gravimetric finish (Au)

0.01 - 1,000 ppm

30 g, Fire assay, AAS finish (Au) gravimetric finish (Ag)

GC_FAG32V

≥ 10 ppm ≥ 0.5 ppm ≥ 10 ppm

GOLD IN PROCESS SOLUTIONS CODE

30 g, Fire assay, gravimetric finish (Au, Ag)

GC_FAG33V

ELEMENT

LIMIT(S)

DESCRIPTION

≥ 0.01 mg/L ≥ 0.01 mg/L

GC_FSA84T GC_FSI84T*

Au Au

Solution, Fire assay, AAS finish Solution, Fire assay, ICP-OES finish

2 - 2,000 ppm 0.01 - 99.5%

Carbon, 1 g, ash, acid digest, extract, AAS finish 100-500 mg, Fire assay, gravimetric finish

GC_ACA22D100V

GC_BUL36V

These methods are also applicable to cyanide liquors. * Pt and Pd can be added to GC_FSI84T.

GOLD IN CYANIDE LIQUORS CODE

ELEMENT

LIMIT(S)

DESCRIPTION

≥ 0.05 mg/L ≥ 0.001 mg/L

GC_AAS82T GC_AAS82X

Au Au

CN solution, AAS finish

Solvent extraction, DIBK, AAS finish

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