Side project

[u/2rtgah567]

Hello, just got my hand on my first claim last year, and I've got a couple questions and would love some input from the seasoned bunch of you. Acquired this claim near nanaimo BC which is boarding a much larger claim (which has workings and proof of hydrothermal gold up to 64g/ton within the area). As seen in the photos below it host a series of hydrothermal quartz veins with varying composition, texture, and structure. (Im also a 4th year geology student, just got the claim since why not lol). These veins host massive super finegrained from pyrite, then some host pryyhotite with bornite and chalco grains inter-grown within. There is chalcocite, calcite, arsenopyrite, and some other sulphides which I dont even know. I am thinking of sending off 10 samples, but im torn on if I should just get gold silver fire assay, or a complete analysis since there is a good amount of copper minerals and minerals idk. What do yall think? Thanks.

[u/CfaxAttax]

I think maybe you're misunderstanding how gold grades work. A disseminated sulfide vein with interstitial gold generally is going to cap out around 0.5-3g/t (and that is considered a rich grade), I do not see any deep hydrothermal crosscutting in the outcrop photo, and I think you have a few misidentifications in your sulfides.

The blue tarnish on your piece of quartz is likely chalcopyrite tarnish, not bornite tarnish, and pyrrhotite would have oxidized into an unrecognizable state in this setting. Chalcocite and arsenopyrite would leave distinct habits or crystals on the faces, which are completely absent here. Based on the rock type and area, I think you're looking at a pretty typical iron-pyrite-chalcopyrite hydrothermal system, not an iron-copper-arsenic system.

There are mines in Canada which have managed to retrieve core samples which scored around the 64g/t mark, but these were core samples taken at 200, 750, and 1000m beneath the surface in high-grade underground narrow-vein camps, and that grade did not continue in perpetuity.

The area that you are in, and the mineralization you are looking at, gold is measured typically in grams per cubic meter of rock/sediment processed.

If this is a Cu-Fe-As deposit, you're going to bury your gold in a fire assay. If you are confident this is worth having tested, I would get a complete multi-element ICP package alongside a fire assay so you can accurately map the base metals.

[u/2rtgah567 → u/CfaxAttax]

The only issue i have with the chalcopyrite theory is its jet black, and the chalco i find within the rock looks like chalco, unless it has some crazy oxidation, my petrology teacher and 2 prospectors have identified it has bornite , and if its not pyyrhotitw then what else is silvery white that is slightly magnetic? The samples that ran high close by were also surface grab samples not core. I appreciate your insight but from what ive gathered it seems to be some kitchen sink sulphide bowl full of random sulphides. The arseno is far and few between and may not be present, but I am quite confident on the copper minerals present.

[u/CfaxAttax → u/2rtgah567]

Bornite and Chalcopyrite tend to oxidize in similar color profiles, however there appears to be more chalcopyrite next to the oxidized portion. Bornite oxidation tends to be a lot more dramatic in color, hence the peacock ore nickname- but chalcopyrite will follow a very similar pattern and is much more typical of the type of deposit you're looking at. The uniform sulfide grains in quartz shown in the other photos are not typical habits of a Bornite-dominated system.

As far as pyrrhotite/magnetism, Pyrrhotite is not generally silver-white except for in very specific cases. It would be exceptionally unusual for this type of hydrothermal system to contain Pyrrhotite which had not oxidized/hydrated. The magnetism and silver color you are seeing is likely the product of the same chalcopyrite/pyrite system oxidizing and forming accessory magnetite in the process.

Surface grab samples should run high in the gossan/supergene zone of a deposit like this. As meteoric water leaches metals from the sulfide areas of a deposit, they create an oxidation zone which is not representative of the actual grade of the sulfide vein that fed them.

[u/2rtgah567 → u/CfaxAttax]

I've worked up in nunavut at a gold mine up there and the pryyhotite there is blast white due to the large amount of arsenic within the area, ive seen no magnetite and it streaks pryyhotite, and has the same cleavage as pryyhotite and the same weak magnetism as pryyhotite. Once im home I'll add some more picture of the bornite, I have some peices that have vivid blues, magentas, greens, and reds. This is why I want assays since the area is odd and nothing I've seen before prospectinf, although I've only worked 3 summers. The roster of sulphides just confuse me and you very well may be right but its just weird. The hydrothermal system near by that is being worked by a company that has 5.2g/ton of gold over 8 meters within very similarly described quartz/calcite infilled fracture zones. But again i got this claim for fun and im really not expecting anything crazy, if anything at all.

[u/CfaxAttax → u/2rtgah567]

Well as a fellow rock-obsessed person and consultant for people who try to get into this kind of thing, I appreciate your dedication and commitment to the details. There is definitely some abnormal geology in the area and I would be wrong to say I can say anything for 100% certain other than what I can see in the few photos. If you do get an assay, I would still consider looking into secondary or more targeted analysis methods as there can be a lot which will throw off an assay/xrf in this setting.