ROCK ID

Joined: 23 Mar 2014 Posts: 1

Found in Virginia

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Posted: Mon Mar 24, 2014 4:38 pm

Hard to say exactly with pictures only, for a start do a streak test on both the blue and green by rubbing the minerals on the underside of your toilet tank lid or any un-glazed tile or ceramic, and note/post the color of the streak for both of the minerals, doing a hardness test would be the next step, after you determine the hardness note/ the results, you can find how to do a mineral hardness test by doing a internet search.

Here's link to a comprehensive mineral chart, in the "Filters" section select the color of the mineral, color of the streak, and hardness, the results will help narrow down the field of possibilities.

http://www.minerals.net/MineralMain.aspx

There are other properties that will narrow down the possible mineral ID, such as the chemical group and crystal group, but these are not as easy for a novice to determine.

Also a more exact general location, other than just Virginia, of where these specimens came from can also help by finding out what minerals are common to that general location, we don't need an address just get us close so the geology of the area can be determined.

Post your results and maybe we can help to determine what you have.

Posted: Mon Mar 24, 2014 8:50 pm

There are certainly more experts on here than me, but the green appears to be epidote. Is the black stuff magnetic? Could be magnetite. The rocks look magnesian at least, probably mafic in composition.

Posted: Mon Mar 24, 2014 9:43 pm

definitely epidote, and you're also probably right about magnetite as well. That material looks very similar to Cranberry Iron Mine ore from Cranberry, NC.
If you find the epidote with pink feldspar, then you have Unakite, i believe the state rock for Virginia. It is named after the Unaka Mountains that border TN/NC. The two pieces with the red material you have don't look like feldspar, but rather an iron stained quartz, but hard to tell from the photos.

-Dave

Posted: Mon Mar 31, 2014 7:07 pm

The green may also be some altered serpentine. Knowing the hardness, streak color and area would help as others have noted.
Some easy hardness tests are to see if it scratches glass, or can be scratched easily by a file.

Posted: Mon Mar 31, 2014 8:07 pm

Tim wrote:

The green may also be some altered serpentine. Knowing the hardness, streak color and area would help as others have noted.
Some easy hardness tests are to see if it scratches glass, or can be scratched easily by a file.

Serpentine will feel "greasy" and have a conchoidal fracture.