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jhw

Amber? Copal? Any ideas?

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jhw

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!

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jhw

Thanks! That would make sense. There's some other sliced ones in the collection. Is the weird lumpy shape typical?

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hemipristis
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

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jhw

Thank you sir!

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Mark Kmiecik

Copal is flammable, and should melt before it ignites. This does look more geological. Carnelian?

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abyssunder

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.

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Randyw
1 hour ago, hemipristis said:

Neither, I'm afraid. It's a gorgeous specimen of agate!  :wub:

 

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

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Sagebrush Steve
1 hour ago, hemipristis said:

Neither, I'm afraid. It's a gorgeous specimen of agate!  :wub:

 

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.

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hemipristis
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.

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Randyw

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.

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hemipristis
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

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JohnBrewer

@ynot May be able to shed some geological light. 

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ynot
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.

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jhw

Yeah, I think you guys nailed it! Thanks again.

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