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Identity HelpIdentification Help

15th Sep 2014 00:50 UTCMarc Gravel

Hello

I purchased a mineral recently which I was told to be Native Bismuth. It was only after I received the mineral did I notice the locality was missing so I inquired about it - unknown. The mineral is dense and weighs about 80g and measures 51x38x25mm. I got a little suspicious about it being Bismuth so I tested the streak and found it wasn't Silver-White but a brownish-red which now has me thinking otherwise. I tried the magnet test and it's not magnetic. I have no clue what it is. Appreciate the help :-)

Hematite

Hematite

Hematite

15th Sep 2014 01:19 UTCPeter Haas

Hematite.

Compare the habit in your last photo with e.g. this one: http://www.mindat.org/photo-427305.html

15th Sep 2014 01:26 UTCMarc Gravel

Thanks Peter - the habit says it all. ;-)

15th Sep 2014 16:37 UTCDonald B Peck Expert

And that streak says the same thing.

15th Sep 2014 19:45 UTCMarc Gravel

I had a hunch it to be Hematite based on the streak but still wasn't confident enough to come out and say that ;-) So many dynamics involved in identifying minerals, the learning curve is steep for the newbie but it's coming along thanks to this great forum! It's been a year for learning! Now to clean and identify the self-collected minerals in my possession :-S

15th Sep 2014 21:21 UTCJosé Zendrera 🌟 Manager

If you check the magnetism with a strong neodimium magnet you should notice that is magnetic.

15th Sep 2014 21:30 UTCFunky Crystals

José, do you suggest a neodimium magnet for checking the magnetism? A simple magnet from a common speaker would be inappropriate for that?

That was a nice tip!

15th Sep 2014 21:38 UTCMarc Gravel

I did try a strong magnet, one thats stuck to my rock hammer but no reaction whatsoever.

16th Sep 2014 02:19 UTCOwen Melfyn Lewis

Marc,

There's strong and then there is strong. The strongest Nd magnets as so strong that, if not carefully handled, they can cause very nasty injuries. The soft iron magnets we are all familiar with are simply not in the same class. Worth some reading up.

16th Sep 2014 10:10 UTCMarc Gravel

Thanks Owen, I'll look that up for sure. I'm not sure what my current magnet is made of, but its a small magnet capable of lifting 100lbs, comes in a steel case with an eyebolt . I got it from Princess Auto and do see they also sell the Nd magnets. I'll pick one those up next time I am there. (tu)

16th Sep 2014 16:06 UTCJames Pool

It is almost certainly hematite as others have said. If you don't mind chipping off a piece you can make it more magnetic by subjecting it to a blow torch flame. A little ID trick that I got from one of the earlier Pough mineral field guides. I wouldn't subject the entire specimen to that treatment as you do get damage that way! After treatment it will obviously react to an ordinary magnet.

Hmm... I wonder if other minerals that only react to extremely strong magnets would benefit from a blow torch treatment? I'll have to do some testing!

16th Sep 2014 16:19 UTCMarc Gravel

Does this method work with all minerals with a metallic lustre?

16th Sep 2014 16:30 UTCRob Woodside 🌟 Manager

James, I suspect your blow torch might be reducing hematite to magnetite? If so, other metallic minerals will reduce to a non magnetic stinking mess.

16th Sep 2014 16:33 UTCJosé Zendrera 🌟 Manager

To check magnetism I use 6 mm diameter Neodimium magnet:

Hematite http://www.mindat.org/photo-422879.html

16th Sep 2014 17:30 UTCReiner Mielke Expert

Those neodinium magnets yield some surprising results. Chlorite ( not sure which species) sticks to them but not arsenopyrite? The magnetic properties given in mineral books will have to be rewritten because hematite is not supposed to be magnetic.

16th Sep 2014 21:36 UTCJosé Zendrera 🌟 Manager

Hematite is not ferrimagnetic http://en.wikipedia.org/wiki/Ferrimagnetism but paramagnetic http://en.wikipedia.org/wiki/Paramagnetism

Neodimium magnets are really strong. In fact, they are able to detect magnetism in all minerals in my colection having Fe in his formula, except sulphides. Can see here: http://www.foro-minerales.com/forum/viewtopic.php?t=8119

17th Sep 2014 16:46 UTCDonald B Peck Expert

Strong neodymium magnets suspended on a thread or length of video tape can detect not only Fe, but also Mn and Cu (not pyrite or chalcocite).

See "Magnetic Susceptibilities of Minerals". USGS Open File Report #99-529. I use two 1 x 3 x 6cm magnets on the end of a 10cm length of video tape; and with a small mirror stuck to the end of the magnets. A light shown on the mirror makes it an optical lever and even small motions are visible from the reflected spot.

18th Sep 2014 02:12 UTCWayne Corwin

I rip open old junk Haed Drives for the magnets :-D

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