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Identity HelpAn old donation specimen in a box

20th Sep 2023 15:41 UTCCaroline Im

08060520017057892954591.jpg
Possibly a midwestern mineral as everything else in the donation was from the midwest. But not 100% of what it could be. Unfortunately no other information was with it. Largest crystal is about 3" long and .25" wide. 

Questions Answered
Can it scratch glass? : No
Can you scratch it with your fingernail? : Unable to test
Is it light/heavy for the size? : Normal

20th Sep 2023 16:02 UTCKevin Conroy Manager

I don't recall ever seeing anything like this from the Midwest USA.   If you mean another country please let us know.

As far as what the mineral might be there are two things that come to mind.  It might by gypsum (or selenite) that is coated with limonite, or maybe stibiconite after stibnite.   If there are any fresh or broken crystals please post more photos.   You can post one photo per reply, so just reply to yourself for as many photos as you would like to add.

20th Sep 2023 16:23 UTCCaroline Im

Thank you Kevin! I only said midwest because a lot of the other specimens from the same donation were from there, but that was not a hard fast rule. 

I posted more photos below, thank you for your help!

20th Sep 2023 16:08 UTCDon Saathoff Expert

My first thought was also stibiconite from Mexico.  I don't recall the mine.  But gypsum is probably more likely.

20th Sep 2023 16:14 UTCCaroline Im

09830880017057892959571.jpg
here's a twinned crystal which is making me think more gypsum. 

20th Sep 2023 16:15 UTCCaroline Im

08696310017057892967985.jpg
The top of a broken crystal which is white and not just glare.

20th Sep 2023 16:34 UTCKevin Conroy Manager

The "fishtail" crystal is typical of gypsum.

20th Sep 2023 16:34 UTCEd Clopton 🌟 Expert

I agree, pretty surely gypsum, but where it's from is another question.  Appears to be in pretty good condition, considering how fragile it has to be.  Must have been well cared for.

20th Sep 2023 18:08 UTCSteve Hardinger 🌟 Expert

Agreed, a cluster of limonite coated gypsum. The fishtail confirms it. As to the locality, 'Midwest' is possible, as this might be a post-mining, evaporation pool artifact.

20th Sep 2023 19:32 UTCDana Slaughter 🌟 Expert

I've seen similar material, though not nearly so encrusted, from the Bristol mine at Crystal Falls, MI. These are post-mining and quite famous among Midwest collectors. It, in all likelihood in my opinion, is not from here but is possible.
 
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