Rocky Posted August 20, 2018 Share Posted August 20, 2018 So a coworker of mine knows I enjoy rocks so he gave me this rock he found at work. Something about this rock rubs me the wrong way for some reason, the black portion almost looks man made kinda like black beauty blasting media packed together in layers, but then it has what I would assume a even layer of quartz stuck to it as well. The shape, the man made appearance, the ultra white layer with ultra black shiny packed inclusions just really bother me. What is it?? Quote Link to comment Share on other sites More sharing options...
adam Posted August 20, 2018 Share Posted August 20, 2018 That is natural. Quartz/Schorl 2 1 Quote Link to comment Share on other sites More sharing options...
Rocky Posted August 20, 2018 Author Share Posted August 20, 2018 7 minutes ago, adam said: That is natural. Quartz/Schorl Thanks Adam, now I can put this away in the cabinet knowing its natural. I appreciate the help. Quote Link to comment Share on other sites More sharing options...
d_day Posted August 20, 2018 Share Posted August 20, 2018 Could be schorl, but I think biotite is more likely. Definitely natural though. Quote Link to comment Share on other sites More sharing options...
Morlock Posted August 20, 2018 Share Posted August 20, 2018 Maybe some type of schist? Quote Link to comment Share on other sites More sharing options...
Bedrock Bob Posted August 20, 2018 Share Posted August 20, 2018 (edited) Absolutely schorl. You can tell for sure by looking at it under a magnifier. Biotite or mica looks completely different and is not nearly that perfectly jet black with reflective faces. The little black quartz crystals look like they are all well formed and easily identifiable with just a little magnification. Mica is flat and tabular and only sparkles in one plane. Little quartz crystal druses are "faceted" and sparkle at all angles as you turn the rock. So I can tell you have angles in those crystals facing all different ways based on just how it sparkles. Mica catches light at one certain angle and schist is highly oriented in a single plane. So with just that observation we can rule out the crystal habit of mica. This is black, granular, high silica and has faces pointing in several directions. It is a dead ringer for black quartz schorl. Edited August 20, 2018 by Bedrock Bob Quote Link to comment Share on other sites More sharing options...
4meter Posted August 22, 2018 Share Posted August 22, 2018 Just from the video the mineral could also be Hornblend, Chloride, Augite or a host of other "black" colored minerals. If Rocky could supply a close up photo, that is in-focus, of the sample and supply some more info such as the results of a hardness & streak tests that would be very helpful. Quote Link to comment Share on other sites More sharing options...
Rocky Posted August 24, 2018 Author Share Posted August 24, 2018 On 8/22/2018 at 12:09 PM, 4meter said: Just from the video the mineral could also be Hornblend, Chloride, Augite or a host of other "black" colored minerals. If Rocky could supply a close up photo, that is in-focus, of the sample and supply some more info such as the results of a hardness & streak tests that would be very helpful. Will do. I can do the others tests as well and fill you in. Quote Link to comment Share on other sites More sharing options...
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