is this gneiss?

Moorestown, NJ(Zone 6b)

Thank you!

Thumbnail by betulo
Calgary, AB(Zone 3b)

No, it's obsidian which is volcanic glass.

Moorestown, NJ(Zone 6b)

Thanks.

Lucketts, VA(Zone 7a)

About 99% sure it is slag, not obsidian.

Calgary, AB(Zone 3b)

The choncoidal fracture and tranlucence indicate glass. What sort of ore refining would result in slag that's made of glass?

Lucketts, VA(Zone 7a)

Lots of small ore smelting operations produce slag, as do some fires. Many rocks contain silica in some form and fires or smelting often produce a glass component. Typically it has a banded vitreous layer bounded by a cinder-like rind or a welded layer of breccia or grains like the specimen showh above. It is commonly found in this part of the country, and I used to have a collection of slag specimens that I encountered on field trips and other outdoor activities.

Post a Reply to this Thread

Please or register to post.

Upload Images to your reply

    You may upload up to 5 images
    BACK TO TOP