What is it?

Posted: Wed Mar 09, 2011 10:05 pm

So I posted a while back about a iron pyrite looking mineral I found while panning. I didnt have pictures at the time but now I do and will post some of them. Now a little about the material in question. It is relatively heavy, I would compare it to panning with garnets. It is found in spots where heavies fall out, behind large rocks in eddies and slack water areas. It takes on many shapes, mainly cylindrical or sperical, with variations of these. Large, small, long short, clustered together etc.

this is a larger piece, about 1cm across.

this is a 'flake' piece at about 2x magnification

Posted: Wed Mar 09, 2011 10:09 pm

this is what it looks like after heating to red hot with a propane torch and breaking.

same piece @ 2X magnification

4x magnification

4x magnification of the 'flake' piece

Sorry, i dont have a streak plate and dont know how to test the hardness. Any help would be appreciated.

Dredger Joined: 22 May 2010 Posts: 605

A small piece of fine sandpaper will do a nice job as a streakplate. Is the material slightly magnetic?

Sam

Posted: Thu Mar 10, 2011 7:02 pm

Hey Sam,

Its only very slightly magnetic. Most pieces are not magnetic. I think only one of the small cylinder shaped pieces was magnetic. And again, just slightly stuck to a rare earth magnet. The sphere shaped piece i checked will scratch glass and a stainless steel swiss army knife blade. the streak is about as dark as number 2 pencil lead. Maybe just a little darker. What other information can I get to try and identify it?

Posted: Fri Apr 08, 2011 8:28 pm

Don't know where you were hunting,but is it possible that it's a musket ball?Just throwing something out

Posted: Fri Apr 08, 2011 9:13 pm

Is it magnetic after being heated? If so then it is pyrite. I was thinking either limonite or pyrite, but the shiny one looks more like regular pyrite to me. Of course my eyes are kind of bad so I cant really tell much from the pics.

The streak seems to match at least, as well as the hardness. Maybe you could do a specific gravity test? That would tell us a lot as well.

Posted: Fri Apr 08, 2011 10:00 pm

I thought the first picture was of a meat ball. Now I am hungry.

Posted: Sat Apr 09, 2011 8:08 am

I have yet to do a specific gravity test. I keep forgetting to take a large enough piece to work (we have scales there). I know the picture quality is horrible. I was trying to use a disecting microscope to magnify the pictures which results in the center of the pic being focused and the edges all blurry. I read the Wikipedia article on limonite. Based on that I would think limonite. I search for gold in a sandstone outcropping in a river. There is not much and its all super fine. I believe there is lots of iron in the surrounding soils, as well as lignite in the sublayers. Thanks for the help in identifying and I will get the SG as soon as I can!

Giorgio, go get you some breakfast! Smile

Posted: Tue Apr 12, 2011 1:06 pm

OK, I checked the SG on two pieces and it is between 3.45 and 3.75. That is lower than iron pyrite.

Posted: Tue Apr 12, 2011 7:54 pm

It's perfect for Limonite, which is 3.4 to 4.3 SG.

Al

Posted: Wed Apr 13, 2011 8:31 am

Limonite is now starting to look like leaverite! Laughing

I have my few specimens for my collection, the rest stays put! Now if only I could find a good use for the stuff. Anyone want some Limonite, I'll sell it to ya, real cheap! Wink