Description
DOWNLOAD AMIS CERTIFICATE (PDF)
AMIS0615 Au 1.068g/t U 15ppm Wits South Africa
Origin of Material
This standard was made using ore material from 3 active pits (SUBIKA, AMOMA and AWONSU) within Newmont Ghana Gold Limited, Ahafo. The Ahafo Project is in south-western Ghana, approximately 300 km northwest from the Capital of Accra. The south-western part of Ghana hosts the Birimian Super-Group which comprises several narrow north-east-trending belts of volcanic and volcaniclastic rocks of tholeiitic to acidic composition. These are separated by broad sedimentary basins dominated by turbidites. The Ahafo projects are in the Sefwi Belt, one of the five Birimian volcanic belts. The Sefwi Belt is bounded to the northwest by the Sunyani Basin and to the southeast by the Kumasi Basin. The Dixcove suite or “belt-type” granitoids intrude the contact and predominate in the metavolcanics that form elongate bodies parallel to the regional strike. Cape Coast or “basin-type” granitoid intrusions are found in the southern-most part of the project area. Regionally, the sedimentary succession consists mainly of fine to medium-grained lithologies (argillites and wackes) with variable amounts of volcaniclastic material. Cape Coast type granitoids intrude the metasediments. The volcanics are mainly basaltic and have been metamorphosed to varying degrees from Lower Greenschist to Amphibolite Facies.
Approximate Mineral and Chemical Composition
Gold mineralization within the Subika deposit in the southern portion of the project area is located within a fracture zone within a host of Dixcove Suite granitoids. Gold mineralization in the southern part of the Sefwi Belt within the Amoma and Awonsu deposits is hosted at or near the contact between the overthrust of the Dixcove granite with underlying meta-volcano sedimentary units. The mineral composition for the Subika samples are: Quartz – 17%, Albite – 54%, Ankerite – 15%, Calcite – 2%, Muscovite – 7%, Chlorite – 2%, Pyrite – 3%. The mineral composition for the Amoma and Awonsu samples are: Quartz – 15%, Plagioclase – 51%, Muscovite – 15%, Chlorite – 2%, Ankerite – 16%, Pyrite – 1%, Calcite/Siderite – trace amounts.
Recommended Concentrations and Limits
(at two Standard Deviations)
Certified Concentrations
Analyte Method Certified (µ)7 (2s)9 ± Unit
Au Pb Collection1 1.068 0.071 g/t
U 4A_MICP2 15 2 ppm
C Combustion/LECO3 852 160 ppm
S Combustion/LECO 0.44 0.04 %
S 4A_MICP 0.45 0.04 %
LOI LOI4 1.67 0.12 %
SG SG5 2.75 0.22 Dimensionless
Ag 4A_MICP 0.6 0.3 ppm
Al 4A_MICP 3.71 0.27 %
As 4A_MICP 70 8 ppm
Ba 4A_MICP 173 19 ppm
Be 4A_MICP 0.6 0.1 ppm
Bi 4A_MICP 0.8 0.09 ppm
Ca 4A_MICP 1080 134 ppm
Cd 4A_MICP 0.2 0.03 ppm
Ce 4A_MICP 36 4 ppm
Co 4A_MICP 24 2 ppm
Cs 4A_MICP 2 0.2 ppm
Cu 4A_MICP 42 4 ppm
Fe 4A_MICP 1.72 0.088 %
Ga 4A_MICP 9 0.5 ppm
Hf 4A_MICP 1 0.5 ppm
K 4A_MICP 9421 236 ppm
La 4A_MICP 19 2 ppm
Li 4A_MICP 23 1 ppm
Lu 4A_MICP 0.1 0.04 ppm
Mg 4A_MICP 4950 279 ppm
Mn 4A_MICP 180 13 ppm
Mo 4A_MICP 3 0.3 ppm
Na 4A_MICP 760 110 ppm
Nb 4A_MICP 2 0.8 ppm
Ni 4A_MICP 77 14 ppm
P 4A_MICP 90 16 ppm
Pb 4A_MICP 37 4 ppm
Rb 4A_MICP 37 1 ppm
Sb 4A_MICP 3 0.6 ppm
Sc 4A_MICP 6 0.4 ppm
Sn 4A_MICP 1 0.1 ppm
Sr 4A_MICP 17 2 ppm
Ta 4A_MICP 0.3 0.1 ppm
Tb 4A_MICP 0.2 0.08 ppm
Th 4A_MICP 5 0.5 ppm
Tl 4A_MICP 0.3 0.06 ppm
V 4A_MICP 35 4 ppm
W 4A_MICP 2 0.3 ppm
Y 4A_MICP 5 2 ppm
Yb 4A_MICP 0.6 0.3 ppm
Zn 4A_MICP 98 6 ppm
Zr 4A_MICP 51 12 ppm
