jhw Posted July 6, 2019 Share Posted July 6, 2019 I inherited a friend's mineral collection. Lot's of interesting specimens of turquoise, petrified wood, crystals, etc. He lived in New Mexico and I know some of the pieces are from U.S. southwest area. That's about all I know. This one's a mystery, and he really didn't have any idea either where it came from. Has a strangely organic look to it though. Any insight or thoughts will be appreciated. Thanks! Quote Link to post Share on other sites
hemipristis Posted July 6, 2019 Share Posted July 6, 2019 Neither, I'm afraid. It's a gorgeous specimen of agate! It resembles Fire Agate, but w/o the fire 4 Quote Link to post Share on other sites
jhw Posted July 6, 2019 Author Share Posted July 6, 2019 Thanks! That would make sense. There's some other sliced ones in the collection. Is the weird lumpy shape typical? Quote Link to post Share on other sites
hemipristis Posted July 6, 2019 Share Posted July 6, 2019 7 minutes ago, jhw said: Thanks! That would make sense. There's some other sliced ones in the collection. Is the weird lumpy shape typical? The shape is called "botryoidal". Numerous minerals exhibit this crystal form, and with regards to agate, it is extremely common. Here are a few examples of other minerals exhibiting this habit, including malachite, calcite, hematite and goethite 3 Quote Link to post Share on other sites
jhw Posted July 6, 2019 Author Share Posted July 6, 2019 Thank you sir! Quote Link to post Share on other sites
Mark Kmiecik Posted July 6, 2019 Share Posted July 6, 2019 Copal is flammable, and should melt before it ignites. This does look more geological. Carnelian? Quote Link to post Share on other sites
abyssunder Posted July 6, 2019 Share Posted July 6, 2019 I have never seen amber with botryoidal crescents, so I'm leaning toward a harder material which may have that pattern. It may have a silica-rich material, in my thinking. 1 Quote Link to post Share on other sites
Randyw Posted July 6, 2019 Share Posted July 6, 2019 1 hour ago, hemipristis said: Neither, I'm afraid. It's a gorgeous specimen of agate! It resembles Fire Agate, but w/o the fire +1 I’m with hemipristis it’s geologic in origin likely an agate. Really beautiful specimen too 1 Quote Link to post Share on other sites
Sagebrush Steve Posted July 6, 2019 Share Posted July 6, 2019 1 hour ago, hemipristis said: Neither, I'm afraid. It's a gorgeous specimen of agate! It resembles Fire Agate, but w/o the fire Yes, it’s fire agate, possibly from Arizona. We used to collect it in a place called Saddle Mountain many, many, many years ago. 2 Quote Link to post Share on other sites
hemipristis Posted July 7, 2019 Share Posted July 7, 2019 9 hours ago, jhw said: Thank you sir! For educational purposes, a few more 'tests'/observations that will help distinguish: Amber/copal are chemically almost natural styrene plastic. As such, they will be very lightweight and soft. A pin or nail will scratch them. One can polish them with toothpaste. Agate/chalcedony in contrast represent varieties of microcrystalline quartz, and will feel, well, as heavy a as a rock, LOL. They will also be sufficiently hard that a pin or nail will not scratch it, and will scratch glass. 1 Quote Link to post Share on other sites
Randyw Posted July 7, 2019 Share Posted July 7, 2019 A quick easy test for amber is to mix 2 cup warm water with 1/4 cup salt. Real amber will float. Copal and most other objects will sink. 2 Quote Link to post Share on other sites
hemipristis Posted July 7, 2019 Share Posted July 7, 2019 1 hour ago, Randyw said: A quick easy test for amber is to mix 2 cup warm water with 1/4 cup salt. Real amber will float. Copal and most other objects will sink. Didn't know that trick. Thanks Quote Link to post Share on other sites
JohnBrewer Posted July 7, 2019 Share Posted July 7, 2019 @ynot May be able to shed some geological light. Quote Link to post Share on other sites
ynot Posted July 7, 2019 Share Posted July 7, 2019 3 hours ago, JohnBrewer said: @ynot May be able to shed some geological light. Don't know what I could say that has not already been said. Quote Link to post Share on other sites
jhw Posted July 9, 2019 Author Share Posted July 9, 2019 Yeah, I think you guys nailed it! Thanks again. Quote Link to post Share on other sites
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