FMF - Friends of Minerals Forum, discussion and message board

[trtlman]

I went to Lake Merwin in Washington State a while back and found it odd that the shores were covered in fragments of pumice. Along with the pumice were other white stones with black specs, hematite? I say hematite because the stones were slightly ferrous. I was wondering if anyone knows anything about Lake Merwin and the minerals it contains and why there is such a large amount of volcanic rock on its shores?

[Riccardo Modanesi]

Hi Tritman!
Interesting! Why don't you show us some photos of minerals you found there, if you have it? For what I know, this is not a so well-known place!
Then, be careful you don't mistake a grizzly grotto for a mine! Hahahahaha!!!!
Greetings from Italy by Riccardo.

[Susan Robinson]

Lake Merwin is a man-made reservoir not far from Mount St. Helens. The area and the volcano have been active for over 40,000 years. I would assume the pumice is from one of the volcano's eruptions. As for the black mineral, I don't know unless you post a few photos. Are you sure the specks aren't little specks of volcanic glass?

[trtlman]

Thanks Susan I never thought of volcanic glass, though I can't think of why it would be ferrous, must contain traces iron since the stones are volcanic. I appreciate the info it was very helpful. I wish I had some photos to share but I took none while I was there and misplaced the minerals I brought home, but it would be of no help any how since I have computer right now, I'm on my tablet. The photos in my other post were borrowed from my facebook page.

[Riccardo Modanesi]

Hi to everybody!
Ok if no photo is shown, I can't say anything, but Susan is right: it might be an obsidiane, there's a kind of it called "apaches tear", in perlite rock, a white one resembling pumice, from the USA (I don't remember where from properly, maybe on Mindat there is something more about).
Greetings from Italy by Riccardo.