Geo-Ing Crazy
starting to spend too much on rocks
Member since March 2008
Posts: 238
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Post by Geo-Ing Crazy on Jul 25, 2009 22:06:41 GMT -5
Got this rock at a yard sale a few months ago for 50 cents. It is about the size of a football and weighs maybe 5-6 pounds. It seems to be made up of a bunch of tiny green "crystals" (more like chunks than crystals) with crumbly gray/black material cementing/encasing them. The whole rock is very crumbly. The green crystals break off very easily are not much bigger than a BB. The crystals will scratch a penny, but will not scratch glass. Just curious if anyone has any ideas . Thanks. Barb Each of these "chunks" actually could be broken into a couple more pieces.
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Jul 28, 2009 15:34:45 GMT -5
Apatite in calcite? An acid test will quickly confirm or disprove. A little bit of pool acid, from any hardware store, hydrochloric aka muriatic, handle with care, protect eyes, skin, lungs, follow instructions on bottle etc. Can't really tell if the xls are six sided, but that's a good indicator of apatite, which will also be etched by acid, but not as vigorously as the calcite.
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Post by catmandewe on Jul 28, 2009 15:42:24 GMT -5
I would guess opalite. I have some of that and the only answer I ever got from the old gentlemen who I get it from was opalite, (but that is what he called everything that he didn't know the name of, so take it with a grain of salt!)
Tony
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Geo-Ing Crazy
starting to spend too much on rocks
Member since March 2008
Posts: 238
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Post by Geo-Ing Crazy on Jul 29, 2009 0:28:23 GMT -5
Thanks guys, I might have to try the acid. What's confusing to me is the the crystals do not appear to be uniform...not consistently 6-sided or whatever-sided. I actually have another rock that I got in the yard sale rock bucket that has some crystals that look quite similar, but they are yellowish brown. Those crystals are on the outside of a rock that has quartz crystals in sort of a geode. I'm probably wrong, but I was wondering if those other crystals are citrine. Can I just add that one here?? quartz crystals AND..yellow? Even if I don't know what it is, it's a kind of cool rock! Thanks Barb
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Post by superioragates on Jul 29, 2009 8:13:51 GMT -5
That almost looks like a laker to me... on the white side....but I know not much about a lot of rocks! It's pretty though, hope someone can help you with this, so I know what it is too!!
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Jul 30, 2009 17:18:06 GMT -5
OK, yes you'd expect nice hexagons from apatite, but they can quite often be squished and malformed, with melted edges even.
The second rock is an agate with a central vug lined with quartz crystals. The brown/yellow material is not crystalline, there's no faces showing there, I'd suggest possibly an amorphous silica at best. Could maybe call it opal, lots of stuff like that in the rhyolite of the Mexican jelly opal mines.
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