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Have a question about how to identify Lepidolite?

0 votes

Hello, I have a few big pieces of mica from NJ, 1. is 1' L. x 11" w. x 3" [1] ht. the other 2 are a few inches smaller and the 4th one is only a few inches big, but it does not look like the pictures you have. They are similar, and the description kind of matches. When I first saw it I thought it was fools gold, because it is bright yellow in color like gold. But then I picked it up and it was flaky. I was wondering how to test it to find out if it is Lepidolite mica? this one is a medium one and it got a little bit of rust on it because it started raining and my husband put our tools in with it. alt text


asked May 23, 2013 by just Shell (240 points)

6 Answers

0 votes

The picture you sent is not so clear. However, much of the light-colored mica that comes from NJ is in the Franklin Marble zone and is phlogopite. Where did you find this piece?

I am not aware of any lepidolite from NJ. Lepidolite originates in lithium-rich pegmatites, which are pretty much non-existent in NJ.

answered May 24, 2013 by hershel (52,800 points)
0 votes

We found them on top of a hugh rock pile that the mine owner said we could dig from, well he called it a rock pile, it was more like a giant hill of rock. Kind of like a strip mine I guess. It was in Belvidere, NJ. I think that's in Warren Co. Here are a few more pics I hope they help.

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answered May 26, 2013 by just Shell (240 points)
0 votes

I just looked up the phlogopite we found that up there also. There was a lot of that actually. We found stuff that I'm still trying to figure out what it is. He cracked open a red rock and thought it was a geode, but it wasn't but is was full of long crystal structures, it is cool looking.

answered May 26, 2013 by just Shell (240 points)
0 votes

That area is outside of the Franklin Marble, so its probably not phlogopite. That area is probably in the Reading Prong metamorphic belt, in which the most common mica is biotite. Its the right color for muscovite but thats not common for the area. Another possibility is eastonite which is an uncommon mica found across the river in Easton, PA.

answered May 29, 2013 by hershel (52,800 points)

Does eastonite have small flakes,and you can wash it? I cleaned some of the rust off of one of them. Some of the flakes came off on the sink but as you can see in the top pic. it did not fall apart. I'm stumped. I looked on here for eastonite but it does not have it.

0 votes

Yes, eastonite has small flakes, and like other micas will shed when washed. Here is a picture of eastonite: http://www.johnbetts-fineminerals.com/jhbnyc/mineralmuseum/picshow.php?id=31340

answered May 30, 2013 by hershel (52,800 points)

That is it, you found it! Thank you so much!!! Wow your awesome! I wonder how they got across the river?

0 votes

They could have been dumped, or the geological formation extends across the river in an undocumented exposure.

answered Jun 4, 2013 by hershel (52,800 points)

I would think the ladder. Only because, we found a bunch, and several of them are pretty big. One is a foot wide and at least 20lbs. We Found a lot of really wild looking minerals up there, I have them in bags. I know a good bit about gemstones but I'm still learning about minerals. I know a bunch of minerals, but wow I never realized how many there actually were. Thank you so much again for your help! I notice you help a lot of people on here. Are you GIA Certified?