I found some black glassy like minerals (I think,but not sure)that is very hard and kind of heavy.I compared it to a chunk of coal and it is not even close to it's weight or hardness but it is close to it's shinny or glassy appearance.
Black glass always sounds like obsidian.
Post a picture and most likely we can confirm....
Ok let's see here (quarter as ref) !
Obsidian is definitely a possibility. Has the right luster and conchoidal fracture. Where did you find these? Are there more of these in the area?
I have found a lot more of this stuff in my area,it is definitely a volcanic glass, there is a large deposit nearby that contains many different colors of it some are even mixed and swirled together.there is some red,brown and black all mixed together along with many other minerals.
The mixed and sworled specimens could have value. Type obsidian into google and hit images. You will see some that are called snowflake obsidian. Some are valuable