• Register

Information for users from the old Q&A site
If you have an account from our old Q&A site, your account was transferred over, but you need to reset your password and confirm your email address.
Reset Password here
Confirm Email here

2,235 questions

3,905 answers


109,811 users

what rock is this?

0 votes

i came across a circle about 4 feet wide that had a large amount of these rocks. any idea what rock it is? i found them in the desert near Yuma, Az. ranging from pebble size to softball size. if broken some seem glass like, dark purple/black and some have shiny flaks of orange/red. some of them seem to have flat sides which makes me wonder if someone dumped them after attempting to shape them?

asked Oct 16, 2018 by oneoftheguys01 (120 points)
edited Oct 17, 2018 by oneoftheguys01

2 Answers

0 votes
Hmm... Where did you find it? It looks metallic, is it magnetic? We need more information in order to identify it..
answered Oct 16, 2018 by linkisnotzelda (5,390 points)
in the desert near Yuma, Az, usa. does not appear to be magnetic. i attached a second pic as well. and thank you
The second picture appears to show some sort of crystal figure within it. Is that area known for metamorphic rocks? It looks metamorphic in origin.
0 votes
Can you test streak or hardness? That would help narrow it down. The bottom picture looks a bit like zircon and it appears to be metamict in form. May also be very rough almandine garnet. Further tests would help to determine what it is.
answered Oct 18, 2018 by hershel (52,800 points)
how would i go about doing a test streak or hardness?
Testing for hardness by scratching with an item of known hardness, a common nail or a jackknife, a piece of quartz. Look up Mohs scale. They will tell you about common items with hardness listed. So if the nail doesn't scratch it but the quartz does you will know a range for the hardness. Simple test.
The streak test is taking an unglazed piece of ceramic tile and scratch the surface of the tile. The streak left behind can give you a clue as to what substance you are looking for. Again you can look up streak tests and find results. It is a tool with which you can rule out certain minerals. Say for instance you have pretty much gotten down to three minerals, two have brown streaks and one has a white streak. You can eliminate one if yours has a brown streak.