Is this harmotome or analcime?

Acquired specimen recently. Dealer claims that it's from the Thura - Tunguska River Basin in Siberia Russia. I can't find any record of harmotome from that location, and the minerals habit reminds me of analcime. So two questions. Has harmotome been found in that location, and based on the picture, what species do you believe it to be? Thanks!

> "...what species do you believe it to be?"

Hi David,

It looks like Analcime to me but you will be the best judge since you have it there. The locality is well known for great examples of Analcime. There are some differences between the two that can help you distinguish one from another. The characteristic shapes of both is a good place to start. Take a look at the crystal atlas rotating animation (especially #2) on the Analcime page here. [www.mindat.org] Does it have any evidence of good cleavage? Harmotome will often show a good cleavage, Analcime won't. Also Analcime is a bit harder. Good luck with it.

Ron



Edited 1 time(s). Last edit at 03/03/2012 03:04PM by Ronald John Gyllenhammer.

I don't know how rare it is, but bear in mind that both harmotome and phillipsite can occur in complex twins with pseudocubic symmetry. I am NOT suggesting that it is the case here, just a possibility.

cheers

I think this is a Analcime group specimen

Those look a lot like the analcimes one would find in the Keweenaw Peninsula of Michigan, another basalt deposit.

Classic analcime sample from Tunguska River locality