please help identify this rock. it is heavier than most. dark brown color. picture is shown with streak test. found in Philadelphia pa. at home demolition site. crystals seem to be different type and color some look black and some clear. some places look bubbley like it was melted. couldn't scratch with a knife.
closed as off-topic by Jan Doggen, user12525, Gimelist, Peter Jansson, Fred Aug 26 at 17:34
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "Questions about rock identification requests are off-topic. For more information, see the announcement on meta." – Jan Doggen, Community, Gimelist, Peter Jansson, Fred
The texture of the third picture and the streak carries to clasify the zone of the dark bubbles as "botroydal hematite".
Hematite is an iron oxyde that leaves a redish streak.
It is common at enrichment supergenic deposits forming the top crust of the ore, named gossan.
It appears sometimes mixed with other iron oxydes but the homogenous streak you noticed make me think your piece is mainly composed by hematite.
A density test would clarify this. If it has not a lot of other iron oxydes it will be close to 5.3 g/cm3, if not it could fall easily to 4 g/cm3or so.
Upgraded: You measured a density of 4.95 g/cm3. We much apreciate your effort providing the data we asked.
Your piece is composed by hematite with some impurities.