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GregC12345




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PostPosted: Jan 15, 2018 16:29    Post subject: Thoughts on this one?  

I recently bought this piece from someone who said it was botryoidal apatite - a rare type of formation from Afghanistan. I know the mineral itself has been found there, but - botryoidal? I've also had a couple people say that it looks a bit more like chalcedony, but the longer striated lines (rather than the 'ball' or globular formations found in such things as what's commonly called 'grape agate') in the piece I have here have me a bit puzzled. Could this be purple botryoidal apatite, or something else completely? Thank you so much for your help. My first post here, and I really appreciate any assistance you all can give.

*I wasn't told a more exact location other than 'Afghanistan' unfortunately. Just tried scratching it against another piece that I know is apatite, and the known specimen did not get scratched by the purple mystery piece. It's roughly 4 inches in length.



IMG_0264.jpg
 Mineral: Apatite (Perhaps?)
 Dimensions: About 10 cm
 Description:
Not sure why it's changing certain words like 'this' to esta in Spanish when I post, and putting in more dashes! Sorry everyone, I actually do pride myself in using correct grammar!
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IMG_0264.jpg


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kushmeja




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PostPosted: Jan 15, 2018 16:46    Post subject: Re: Thoughts on this one?  

I'm not certain about your piece specifically, but there for sure apatite that is found with botryoidal formations. I've personally seen specimens from Russia and also from Ojuela Mine in Mexico.

Based on your scratch test, your pictured piece cannot be Chalcedony (Quartz)... otherwise it would have scratched the other specimen that was known apatite, since apatite has a hardness of 5 roughly and quartz is around 7.
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GregC12345




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PostPosted: Jan 15, 2018 16:49    Post subject: Re: Thoughts on this one?  

Thank you Kushmeja. I just tried again to confirm my findings, and a piece of golden apatite (and I'm positive THAT one is apatite) did leave a white scratch on the purple mystery piece. So where does that leave things? Would that mean that this is likely purple apatite after all? :)
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Pete Modreski
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PostPosted: Jan 16, 2018 15:13    Post subject: Re: Thoughts on this one?  

Greg, since doing a scratch test for hardness is the means of testing that you most readily have at your disposal, and if you can do a few more scratch tests on an inconspicuous part of the mineral formations without too obviously marring their appearance, here are some suggestions of what to do:
The simplest thing is to try to scratch the specimen, very carefully, with the point of a pocket knife. If it's apatite you should be able to scratch it easily; if quartz/chalcedony, the knife shouldn't scratch it at all. Remember: scratch "firmly but gently"; if you press too hard, you'll likely just crush the crystals, which isn't a true "scratch". If its hardness is truly less than that of the knife--then apatite is the most likely candidate.
Doing a few more scratch tests: for the test to be most reliable, one needs to use a sharp point on the mineral that does the scratching, and, a clean, smooth, flat surface (a crystal face or a cleavage surface, or a polished face) on the mineral being scratched. The clusters on your specimen look like they would be "difficult" to test on both counts--limited places with good, sharp, angular points to scratch with, and smooth, flat surfaces to scratch. Using a magnifying glass while doing the scratch test may help. Then, for confirmation, it is best to do the test both ways: try to scratch A with B, then reverse and try to scratch B with A. So, you should try doing the scratch test both ways, using, let's say, feldspar (H=6), known apatite (H=5), and fluorite (H=4). A mineral (apatite) should be able to scratch another sample of itself, though with difficulty (the results may be hard to interpret). So if you confirm with certainty that your unknown mineral has H > 4, H < 6, and seems to "approximate" H = 5, then you can be reasonably sure it is apatite.
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GregC12345




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PostPosted: Jan 17, 2018 00:50    Post subject: Re: Thoughts on this one?  

Thank you for the info and advice. I did some additional hardness testing today. The purple mystery piece did scratch when I pressed a bit with a piece of what I am positive is golden apatite. I also tried with a piece of fluorite - the purple specimen did not get scratched by that, but DID fairly easily get scratched by a small pocket knife. So, I'm thinking it's now looking like it may in fact be apatite after all.....even if the shape/form is a bit odd for such a mineral.
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