short term trading: week beginning - 19 aug , page-51

Freehold,
EXS,
I quote tradeforprofit thread on stock board:

Tweets...

There is no question the core contains mainly chalcopyrite (CPY) and will grade well...but the red-beige sulphide could either be pyrite or pyrrhotite...depending on how the light is hitting the core.

Pyrite is not generally red-beige brown in colour and typically looks more "white" than CPY.

Compare your core to the below example of pyrrhotite dominant sulphide ore from Havilah's Mutooroo Copper-Cobalt Project;


Primary Sulphide - pyrrhotite dominant – chalcopyrite - pyrite, disseminated and massive sulphide mineralisation. High grade, primary sulphide milled breccia mineralisation is typically composed of pyrrhotite (60%) - quartz fragments (25%) - pyrite (5%) - chalcopyrite (5%) with local fragments of variably altered country rock.

Now, compare this to the EXS photo...


"Massive sulphides" but no mention of what type?

As can be clearly seen though, the copper mineral chalcopyrite (green-yellow) is far more dominant in the EXS image than it is in the Havilah image.

Below is an example of chalcopyrite (bottom half) and pyrite (top half) from Namibian Copper NL, with no pyrrhotite;


Massive segregation of chalcopyrite and pyrite in magnetite quartzite in drill core

Assay results will tell you how much Cu, Co, Au, Ag, S, Fe, As, etc, etc...is in the core, but will not tell you if pyrrhotite is present...all you will get is a hint of higher Fe and/or S in the results (pyrrhotite being an iron-sulphide is high in Fe and S, but so too are chalcopyrite and pyrite). Generally, to find out of it is pyrrhotite, the geo's test to see if it is magnetic...although, because pyrrohtite is an unusual iron-sulphide with variable iron content, you can get non-magnetitc pyrrhotite (called troilite?).

To identify exact mineral species one needs to use XRD analysis...which provides a break-down of the chemistry of the sample, including atomic arrangement, which is ultimately what differentiates one mineral from another.

Cheers!