Exploration for porphyry-style copper mineralisation near Llandeloy

PHYSICAL PROPERTY MEASUREMENTS ON
BOREHOLE CORES
Magnetic susceptibility
kpparent susceptibility was measured with a
'Kappameter' at intervals of about one metre along the
cores. Segments tested were unsplit and at least 100 mm
long. True susceptibility was obtained by application of a
factor dependent on core diameter. For accuracy better
than 5% the diameter should be greater than 60 mm but
at Llandeloy most core was either 50 or 25 mm in
diameter, so somewhat greater errors are likely
particularly in the higher susceptibility values.
The detailed results are given in Table A4.1
Density
Fourteen lengths of core were chosen to represent the
main rock-types roughly in proportion to their
occurrences in the eight boreholes. Each core was broken
into 2 or 3 samples to provide a check. The samples were
saturated with water under vacuum for 24 hours, then
weighed in water (Ww) and in air (wale After drying in an
oven for 48 hours, they were weighed in air again (Wd).
Then:
Saturated density ps = Wa/(Wa - Ww)
Dry density pd = wd/(wa - Ww)
Grain density pg = Wd/(Wd - Ww)
Effective porosity = (wa - wd)/(wa - Ww)
The results are presented in Table A4.2
Table A4.1:
Magnetic Susceptibilities of Borehole Cores from
Llandeloy, Dyfed
Depths in metres
Susceptibilities (K) in SI Units x 10-3
Borehole 1 (diameter of core 50 mm)
Depth K
Depth
Borehole 2 (diameter of core 50 mm)
Depth K
Borehole 3A (diameter of core 50 mm)
Depth K