There is a rock/fossil thread on here.. Could try posting in that if you can't get answer here. Have no idea what it is but I know I have seen these type rocks before in stores and stuff.
If it is an amethyst, Koolaid, it couldn't be more than 2" across at most. Not too many amethyst crystals larger than that. I vote a variety of obsidian.
The only amethyst deposit in California I have heard of is in Shaver Lake and it is underwater in the lake so I don,t believe it is amethyst.Probably obsidian.
I have checked out all the rocks and my rock looks like purple glass from what I see it looks most like an amethyst. It really doesn't look like obsidian
I will post pictures of it after taking it in sunlight
The river is near clearlake the biggest lake in california I believe. I Have heard it has many different kinds of crystals and some kind of knock off diamonds
I agree with Charlie P. ... this looks to "broken and shinny" to have been dug from mother earth . So I'm stickin' along with Charlie P. and my visual ID is glass or Slag used to decorate aquariums and gardens ... in fact I think I have some in the garden now ... IMHO , Woodstock
You think its glass really?
iT does look like some different color stone is in it like a white boarder or a floating rock. I am taking photos with my notebook so they arent very good I cant find my cam