This was given to me by my grandmother of 89 years, attached to the bottom is an index card which reads:
“Volcanic Glass with Cristobalite Formation on the inside. Belonged to a family from Indiana, this belonged to their family from before the 19th century. Formed during the Ice Age.”
The last part, about the ice age, comes apparently from when my grandmother took this heavy thing to a geologist in her younger years who identified it as such. But I’ve been researching this stone and it shares an extremely similar appearance to Olivine, but has a more striking, sea green color… as well as spherical white ‘bubbles’ on the inside(presumably the Cristobalite?)and some rougher-looking ones protruding on the outside.
Here’s a rough picture from my cell phone, hope it does. I’d be thankful for any information or direction. I really wanna know what this stone is, especially since it seems to have a history, it interests me very much.
The chunk of stone is about half the length of my keyboard and maybe six inches ‘tall.’ It’s a real heavy lift.
It looks like green volcanic glass to me. My stepfather worked on the Alcova Dam project in Wyoming back in the ’30s. He told me that when they dug the diversion tunnel, it went through a vein of about 10 feet thickness. He still had a piece of the material, and it looked quite like your picture.