FMF - Friends of Minerals Forum, discussion and message board

[nora]

This is a beautiful piece of rock it looks like glass, one of the pieces has cobalt blue viens, the other has a purple vien they are really beautiful

[Susan Robinson]

You're right - it's glass.

[Viktorian]

Hi Nora
Unfortunately, what you have in the picture is just glass.I also received such specimens, from USA-Georgia-Helen.
I hope not to be disappointed!
with friendship....Victor

[trtlman]

Yep, decorative glass, commonly used in decorating aquariums or adorning backyard ponds

[Rick S.]

Even though this is "glass" it more commonly referred to as slag. Slag is rough glass with impurities in it which is what causes the color swirls. There are people who collect minerals who also collect slag because of its pretty colors. I have also seen some pretty nice jewelry made from it. Its not a mineral per-se but it IS mineral related.
One common place to find slag is around old Iron furnaces where it was produced during the ore smelting process. The slag was the part of the molten ore that floated to the surface with all the impurities in it and was discarded. For a good web site about the iron industry try:
https://www.betweenthelakes.com/iron/iron.htm
(link normalized by FMF)