Gold Ore Reference Material KH1
Recommended Value and 95% Confidence Intervals
Gold concentration: 0.85 (+/-0.02) µg/g 0.0249 (+/- 0.0005) oz/ton
The above value applies only to sachets which have
a unique identification number within
the following range: (The unique number range is not given on
website for security reasons.)
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Prepared and Certified By: |
Malcolm Smith BSc, MNZIC
Laboratory Consultant
2 Morriggia Place
Auckland
NEW ZEALAND
Telephone: +64 9 444 7194
Telefax: +64 9 444 7739
Email: mgs@xtra.co.nz
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Date of Certification: |
8 August 1997
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Certificate Status: |
Final
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Available Sachet Types: |
This reference material has been packed in nominal
50g and 30g sized sachets and is sold with either a
Geocheck or Labcheck label.
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Origin of Reference Material: |
Sodium feldspar with minor quantities of quartz
and iron pyrites. The gold is present only in
the iron pyrites, which has been finely
ground and leached with cyanide to remove
the free gold.
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Supplier of Reference Material: |
Rocklabs Ltd
P O Box 18 142
Auckland
NEW ZEALAND
Telephone: +64 9 634 7696
Telefax: +64 9 634 6896
Email: rocklabs@clear.net.nz
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Description: |
The component minerals have been well mixed and
a homogeneity test carried out after sacheting
to ascertain that the gold is evenly distributed
throughout the standard. There is no soil
component. The product may contain crystalline
quartz and therefore dust from it should
not be inhaled.
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The approximate chemical composition is:
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(Uncertified Values) |
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% |
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SiO2 |
64.69
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Al2O3 |
17.27
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Na2O
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9.16
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K2O
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0.40
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CaO
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0.44
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MgO
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0.17
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TiO2 |
0.08
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MnO
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0.01
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P2O5 |
0.16
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Fe
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2.97
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S
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3.27
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Intended Use: |
This standard is designed for every batch use for
quality monitoring purposes.
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Stability: |
The sachet and its contents should not be heated
to temperatures higher than 80°C. The sachet
is made from a polyethylene/aluminum foil/paper
laminate and is water resistant. The reference
material inside is likely to last indefinitely.
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Instructions for Use: |
Cut open sachet.
Do NOT dry before weighing.
Weigh out quantity normally taken for analysis.
Assay for gold by usual procedure.
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Method of Preparation: |
Finely ground sodium feldspar was blended with
an iron pyrites concentrate which had been finely ground
and cyanided to remove any free gold that may
have been present. Once the powders were
uniformly mixed the composite was placed
into sachets. Approximately 8200 30g sachets
and 4900 50g sachets were prepared. After sacheting
was completed, sachets were selected at regular intervals
from the packaging run in order to carry out
a formal homogeneity test.
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Homogeneity Test: |
72 sachets (equal to greater than three times the
cube rootof the total number of sachets produced,
including both 30 gram and 50 gram sachets) were
sampled at regular intervals from the packaging
run. These were analyzed and the results
compared with a batch of 12 sub-samples
of the same raw material which had been ground
in a Rocklabs ring mill, mixed by mat rolling
and coned and quartered to obtained 30g
portions for analysis. The ratio of the
variances of the two groups was compared
to the relevant F value at the 95% level of probability.
The conclusion of the comparison was the acceptance
of the null hypothesis of no difference between
the groups. The homogeneity test of the reference material
in its packaged form is based on 30g analyses. If
smaller portions are taken for analysis the same degree
of homogeneity can not be guaranteed.
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Analytical Methodology: |
Once homogeneity had been established two sachets
(one 30g and one 50g ) were submitted to 19 well established
laboratories in order to assign a gold value by
consensus testing. Each laboratory was asked
to carry out the analysis by fire assay
and to analyze only 30g portions from each
of the two sachets.
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Calculation of Certified Values: |
19 sets of results were returned. Cochran's
and Grubbs statistical tests were applied. No
outliers were identified from Cochran's test.
The Grubbs test identified one set of results
as being an outlier. This set of results
was removed and an assigned value was calculated
from the unweighted mean of the averages
of the remaining 18 sets of replicate results. The
95 % confidence limits were calculated from the standard
deviation of the 18 averages. The assigned value is
provided at the beginning of the certificate
in both µg/g (ppm) and oz/ton units.
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Participating Laboratories
Australia
Amdel Laboratories Ltd, Adelaide
Amdel Laboratories Ltd, Perth
Analabs Pty Ltd, Perth
Assaycorp, Pine Creek
Australian Laboratory Services P/L, Brisbane
E nviromet Operations Pty Ltd, Sydney
Genalysis Laboratory Services Pty Ltd, Perth
Canada
Acme Analytical Laboratories Ltd, Vancouver
Activation Laboratories Ltd, Ontario
Chemex Labs, Vancouver
Intertek Testing Services Bondar Clegg, Vancouver
XRAL Laboratories, Ontario
New Zealand
Grayson Laboratories Ltd, Otago
SGS New Zealand Ltd, Waihi
United Kingdom
Anamet Services (Rio Tinto), Bristol
United States of America
Barrick Goldstrike Mines Inc, Nevada
Chemex Labs, Nevada
Cone Geochemical Inc, Colorado
Newmont Gold Company, Nevada
Legal Notice
This certificate and the reference material described
in it have been prepared with due care and attention.
However Rocklabs Ltd or Malcolm Smith accept no liability
for any decisions or actions taken following the use
of the reference material. Our liability is limited
solely to the cost 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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Certifying Officer |
Checked by Independent Statistician |
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M G Smith BSc, MNZIC
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D Tebbutt BSc
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