Spoons Posted March 28, 2020 Share Posted March 28, 2020 Hey Everyone! I have a question for all of you! I was walking along the Eel River here in Northern California looking for fossils from the Pleistocene. The river bars here are full of debris from farther up into the Klamath Mountains of the Coast Ranges. Every so often I like to split open other rocks that I know arent fossiliferous, and so was the case for this rock. Once split open I immediately noticed the bright yellow crystals. My question to all of you... what mineral is this? I thought at first yellow calcite but when I preformed an acid test it was totally inert. This makes me suspect quartz and the individual grains seem to confirm it. To my knowledge citrine crystals should exhibit a dichroic property and I think I see that exhibited in my sample as well. Mindat lists known localities for citrine quartz all over Northern California but all of them are about 150 miles from my location and absolutely nowhere near the headwaters for the Eel River system. Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted March 28, 2020 Share Posted March 28, 2020 Are they cubic? If so they could be flourite. Try a hardness test. 1 Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
Darktooth Posted March 28, 2020 Share Posted March 28, 2020 Could you try to take a close-up of the Crystals? Naturally occurring citrine is actually quite rare. Possibly these are a different mineral or the crystals could be coated with iron oxide which will make them look like citrine from afar. A close-up will either confirm or deny. 1 I like Trilo-butts and I cannot lie. Link to comment Share on other sites More sharing options...
Spoons Posted March 28, 2020 Author Share Posted March 28, 2020 10 minutes ago, Darktooth said: Could you try to take a close-up of the Crystals? Naturally occurring citrine is actually quite rare. Possibly these are a different mineral or the crystals could be coated with iron oxide which will make them look like citrine from afar. A close-up will either confirm or deny. Ahh sorry you guys it takes awhile to fully flesh out my topic on my phone. Hope those photos suffice for closeups. Link to comment Share on other sites More sharing options...
Spoons Posted March 28, 2020 Author Share Posted March 28, 2020 15 minutes ago, Tidgy's Dad said: Are they cubic? If so they could be flourite. Try a hardness test. Let me find a piece of glass I can scratch real quick. Edit: Just put a scratch in my patio table, don’t tell anyone. It easily scratches glass and leaves behind a visible mark after being rubbed. Link to comment Share on other sites More sharing options...
Darktooth Posted March 28, 2020 Share Posted March 28, 2020 The last 2 pics weren't showing up for me when I posted my comment. It is difficult to be 100% sure but it they do look like quartz crystals. But it also appears to look like an iron oxide coating. This happens occasionally at the Herkimer Diamond mines. One of the pay sites sell a special acid to help remove the film, but soaking in citric acid or vinegar for a bit with usually work with a tooth brush and elbow grease. I like Trilo-butts and I cannot lie. Link to comment Share on other sites More sharing options...
Spoons Posted March 28, 2020 Author Share Posted March 28, 2020 2 minutes ago, Darktooth said: The last 2 pics weren't showing up for me when I posted my comment. It is difficult to be 100% sure but it they do look like quartz crystals. But it also appears to look like an iron oxide coating. This happens occasionally at the Herkimer Diamond mines. One of the pay sites sell a special acid to help remove the film, but soaking in citric acid or vinegar for a bit with usually work with a tooth brush and elbow grease. I’ll try that. If it does work should we expect the crystals to take on a more traditional quartz whit color? Link to comment Share on other sites More sharing options...
daves64 Posted March 28, 2020 Share Posted March 28, 2020 Personally I'd either leave them as is, or just do one of the rock pieces. If it is an iron oxide film, it may come off using something like Rust Out, which is readily available at hardware stores & the like. 1 Accomplishing the impossible means only that the boss will add it to your regular duties. Link to comment Share on other sites More sharing options...
Tidgy's Dad Posted March 28, 2020 Share Posted March 28, 2020 The matrix looks like an igneous rock, possibly a metamorphic one. Citrine is effectively just heated amethyst, so it's possible. Life's Good! Tortoise Friend. Link to comment Share on other sites More sharing options...
Spoons Posted March 28, 2020 Author Share Posted March 28, 2020 After an hour in a vinegar bath and some tooth brush scrubbing under hot water, here’s what this piece looks like. 1 Link to comment Share on other sites More sharing options...
ynot Posted March 29, 2020 Share Posted March 29, 2020 Quartz with an iron oxide stain, not citrine. It is very common to find iron coated quartz that color in California. Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
Spoons Posted March 29, 2020 Author Share Posted March 29, 2020 10 hours ago, ynot said: Quartz with an iron oxide stain, not citrine. It is very common to find iron coated quartz that color in California. If it treat it with rust remover will that be a diagnostic test? If it had an iron oxide coating then it should all disappear? What about the dichroic property in some of the crystals? Would that be caused by an iron oxide coating as well? Link to comment Share on other sites More sharing options...
ynot Posted March 29, 2020 Share Posted March 29, 2020 8 hours ago, Spoons said: If it treat it with rust remover will that be a diagnostic test? If it had an iron oxide coating then it should all disappear? Not really diagnostic. It may not remove the material between the parts of the vein. 8 hours ago, Spoons said: What about the dichroic property in some of the crystals? Would that be caused by an iron oxide coating as well? Possibly or by refraction between the individual fragments. Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
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