These are low cost, quality control aids used on an "every batch" basis to monitor the analytical process. The standards consist of pulverized rock with known gold content and suitable for analysis by fire assay or aqua regia digest. These standards are becoming the reference by which gold assay labs check their analysis as well, these standards are used by geologists who can submit a quantity of this reference materials in sachets together with their samples to laboratories to ensure accuracy and consistency.

These Reference Materials are prepared from mineral matrices that contain gold which is uniformly distributed throughout the pulverized rock. These standards are unique in that the gold does not settle out over time or with vibration.

Once appropriate material has been prepared and been confirmed as suitable by laboratory analysis it is packaged in to sachets or jars. A full homogeneity test is then carried out on a representative number of sub-samples from the packaged batch. If there is no significant difference found between the sub-samples then the gold content is determined by consensus testing using a minimum of 15 reputable laboratories from several different countries. Standard statistical techniques are used to assign a recommended gold value with associated 95% confidence interval. Each sachet or jar is labeled with a unique number. A certificate, which includes details of the production and characterization of the Reference Material, is issued with each consignment of sachets or jars sold

Laboratories will use them as part of their normal quality control process. Competent laboratories already do this but often they use "standards" which they have made themselves and which have not been subjected to rigorous homogeneity tests or had the gold concentration accurately determined through analysis by a large number of quality laboratories. Laboratories may prefer to use Reference Materials packed in wide-mouthed jars and which contain 2.5kg. Jars of Reference Material have been tested to check that the gold does not settle out from vibrations, eg during transport.Exploration and mine geologists can submit one sachet (option of 30g or 50g sizes available) with every batch of samples they send to the laboratory for gold analysis. If they send large batches they may choose to include one sachet with every 50 samples submitted. The sachets are robust and can be "thrown" in with their other samples. Because the sachets are sealed it does not matter if they get dirty or wet on the outside. Sachets are supplied with a "Geocheck" label when used by geologists submitting samples to a laboratory. They have a unique number on every sachet, but do not have the name of the Reference Material on the label.

Customised Reference Materials

Do you have mine material or an exploration target which has an unusual matrix? We can make Reference Material for you from your rock!

The mineralised rock will be dried at 105°C, pulverized, and screened to remove any coarse gold which might be present. The screen aperture size chosen will depend on expected gold values. The screened material will be thoroughly mixed, then packaged in either sachets or jars and a homogeneity test carried out.

Samples can be sent out for consensus testing and a formal certificate supplied if required.

Assigned Values &
Confidence Intervals

Perth Stock

Reference
Material

Matrix Type

Gold (ppm)

Silver (ppm)

Box - Sachets
100 x 50g 

Jars
2.5 kg

AuBlank3

Oxide

< 0.002

1

0

OxA45

Oxide

0.0811  (± 0.0026)

Not Assayed

5

-

OxA59

Oxide

0.0817(± 0.0021)

Not Assayed

0

8

OxC58

Oxide

0.201(± 0.003)

Not Assayed

5

0

SE29

Sulphide(2.5% S)

0.597(± 0.011)

Not Assayed

4

9

OxE56

Oxide

0.611(± 0.006)

Not Assayed

2

18

OxF53

Oxide

0.810(± 0.011)

Not Assayed

-

8

SF12

Sulphide(2.8% S)

0.819(± 0.012)

Not Assayed

2

-

SF30

Sulphide(2.8% S)

0.832(± 0.008)

Not Assayed

3

15

SG31

Sulphide(2.8% S)

0.996(± 0.012)

11.12(± 0.46)

4

38

OxG70

Oxide

1.007(± 0.013)

Not Assayed

0

0

OxG60

Oxide

1.025(± 0.011)

Not Assayed

4

0

OxG46

Oxide

1.037(± 0.016)

Not Assayed

1

0

OxH55

Oxide

1.282(± 0.015)

Not Assayed

5

6

SH35

Sulphide(3.0% S)

1.323(± 0.016)

Not Assayed

0

0

SH24

Sulphide(3.0% S)

1.326(± 0.016)

Not Assayed

5

32

Si42

Sulphide(3.0% S)

1.761(± 0.021)

Not Assayed

0

0

SI25

Sulphide(2.9% S)

1.801(± 0.018)

33.25(± 0.61)

1

-

SI15

Sulphide(2.9% S)

1.805(± 0.028)

19.68(± 0.46)

1

-

Oxi67

Oxide

1.817(± 0.019)

Not Assayed

0

0

OxI40

Oxide

1.857(± 0.019)

Not Assayed

1

-

OxI54

Oxide

1.868(± 0.026)

Not Assayed

2

8

OxJ64

Oxide

2.366(± 0.031)

Not Assayed

2

11

OxJ47

Oxide

2.384(± 0.020)

Not Assayed

1

15

OxJ36

Oxide

2.398(± 0.031)

Not Assayed

1

-

SJ22

Sulphide(3.0% S)

2.604(± 0.019)

Not Assayed

1

-

SJ39

Sulphide(3.0% S)

2.641(± 0.033)

Not Assayed

4

3

HiSilK2

Sulphide(1.0% S)

3.474(± 0.034)

Not Assayed

0

0

SK43

Oxide

4.086(± 0.036)

Not Assayed

0

0

OxL34

Oxide

5.758(± 0.071)

Not Assayed

1

-

OxL51

Oxide

5.850(± 0.051)

Not Assayed

1

-

OxL25

Oxide

5.852(± 0.048)

Not Assayed

2

-

OxL63

Oxide

5.865(± 0.055)

Not Assayed

2

12

SL46

Sulphide

5.867(± 0.066)

Not Assayed

0

0

SL34

Sulphide

5.893(± 0.073)

Not Assayed

0

44

OxN33

Oxide

7.378(± 0.088)

Not Assayed

3

-

OxN49

Oxide

7.635(± 0.080)

Not Assayed

1

-

OxN62

Oxide

7.706(± 0.046)

Not Assayed

4

9

SN16

Sulphide(3.2% S)

8.367(± 0.087)

17.64(± 0.42)

1

-

SN26

Sulphide(3.2% S)

8.543(± 0.072)

19.63(± 0.37)

5

-

SN38

Sulphide(3.2% S)

8.573(± 0.061)

Not Assayed

0

0

HiSilP1

Sulphide(2.0% S)

12.050(± 0.13)

Not Assayed

0

0

OxP50

Oxide

14.89(± 0.33)

Not Assayed

2

-

OxP61

Oxide

14.93(± 0.13)

15.99(± 0.43)

0

9

OxP32

Oxide

14.99(± 0.18)

15.99(± 0.43)

2

-

OxM16

Oxide

15.15(± 0.13)

15.53(± 0.46)

2

-

SP27

Sulphide(3.5% S)

18.10(± 0.27)

58.38(± 2.03)

3

-

SP37

Sulphide(3.5% S)

18.14(± 0.15)

Not Assayed

0

12

SQ36

Sulphide(3.5% S)

30.04(± 0.24)

Not Assayed

0

0

SQ28

Sulphide(3.5% S)

30.14(± 0.30)

11.02(± 0.6)

5

0

Pandora Pack

Oxide

on request

on request

  1 x 96 x 50g sachets

-

Pandora Pack

Sulphide

on request

on request

   0 x 96 x 50g sachets

-