• 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

2,237 questions

3,912 answers


128,534 users

Can anybody help me to identify this piece of rock? Sounds like iron slag but the composition does not.

+1 vote

This piece is very heavy, the bottom part is very flat and the color is black. The bottom part attracts the magnet, on the contrary, the top and the sides does not.
The appearance is yellowish but the bottom part looks black. 
First my guess was iron slag  but as I took the XRD test I noticed the low contents of CaO ( Unlike the iron slag <50%). 
It also has high amount of Vanadium and relatively high chromite. 

I would appreciate your thought on the origin? Is it rock or slag ? what type of slag could be?

Thanks in advance 

asked Oct 21, 2018 by vahid (130 points)

2 Answers

+1 vote

From your sheet of composition, it is mostly SiO2. Silicon dioxide 36 %. Some Vanadium, 20%. And then by percentage ferrous oxide, 14%, and finally 10 percent aluminum. The rest are trace metals. It looks like a piece of industrial slag. It is magnetic from at the very least its ferrous content. The silicon dioxide is one third of your composition.  Not magnetic.

Vanadium is used in the production of steel especially drill bits and engine parts, where the steel is going to be subject to high heat.

answered Oct 22, 2018 by Weasel (58,980 points)
Thanks for your kind answer. Could you please tell what do you mean by industrial slag?
Slag is metal waste from processing metals. Steel is made and vanadium added to protect the metal from extremes of heat like in the manufacture of drill bits and engines. The waste metal is disposed of and enters the environmental processes of erosion, weathering and rock making. A concretion of silicates, sand, mud and silica in solution solidifies around the waste and you have a rock with iron, vanadium and silicate.
Dear Weasel

Thanks again for your clarification.  As you mentioned this sounds like a slag but my question is that what type of slag is this?
Since the slag from magnetic iron ore from converter of iron smelting have around 3% V2O5 but this one has a high content of V2O5.
Do you think this is the slag of steel making which ferro Vanadium is added to in EAF?
0 votes
Without any locality data or good crystal habits or pictures, its hard to tell. But not too many minerals are magnetic, and from your description and the magnetism, chromite seems the most likely guess.
answered Jun 6, 2019 by hershel (52,800 points)