Analysis Number
2227808
Petrology Number
2695969
Historical Petrology Number
Analyst
BOCKMANN, M.J.
Petrology Analysis Date
27/05/2019
Thin Section in Storage
Y
Petrology Specimen Type
Polished Thin Section
Lithology
Metagranite
Summary Decription
Detailed Decription
This rock appears heavily altered, with only a few islands of quartz (often disaggregated) in a network of veins interpreted to be remnant from the unaltered protolith (Image 429799 e-f).
Four distinct sets of veins have been identified.
An early phase of fine calcite veins (<50 μm wide) are seen cutting primary quartz at high angles to the main orientation of veins.
These veins are then truncated by the main stage of alteration by sericite. Dispersed among the sericitic alteration are domains of fine-grained quartz with indistinguishable extinction angles. These domains are interpreted to represent a single grain from the protolith, which has then been disaggregated during alteration. The minor pyrite and galena mineralisation in this sample is most commonly associated with this phase of alteration.
Overprinting this phase is a set of subparallel-trending curvilinear quartz veins (Image 429799 c-d). These veins are up to 2 mm wide and contain quartz grains between 10–300 μm, with the finer grains commonly located at the outer edges of the vein.
Finally, a set of fine (<20 μm) unmineralised calcite veins are seen cross cutting quartz veins at high angles, in a similar orientation to the first set of veins described.
Mineral Abundances by Volume
Abundant > 70%
Major 30-70%
Quartz, Sericite
Minor 5-29%
Trace 1-4%
Calcite
Rare <1%
Galena, Monazite, Pyrite, Zircon
Unknown abundance
Rock Sample Petrology information pending.