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Identity HelpBlack mineral from Saint Ferdinand Quebec

17th Nov 2009 04:57 UTCFred A. Schuster

I apologize I didnt have time time to run more tests on this piece, but I am looking for just some ideas from what info I have.

I decided to look for white quartz rocks in a steam running in Saint Ferdinand Quebec..

This village is about 20 minutes from Thertford mines south west.

The area has hills with schist, and some marble and sandstone layers related to the Japetus ocean folded sediments near the serpentine "subduction zone" whatever .... Maybe someone is familiar to the geology.

There were a few gold and copper prospects near, like in Chester according to a Quebec Natural resources mine map

This rock seem dense, heavy. the heft made me think magnetite., in a schist. the schist is like micaceous, maybe talc?

But the dense black mineral is not magnetic. The luster may be more vitreous then metalic after all. But look at the strange shape of the platey crystals. what could it be. any ideas?

Perhaps it was carried by glacier from another region.

dont know what to do with it.

Fred

attachd 2 photos

17th Nov 2009 07:08 UTCKnut Eldjarn 🌟 Manager

Ilmenite or hematite ? Try a streak test on unglazed porcelain (red-brown for hematite, grey for ilmenite).

Knut

17th Nov 2009 09:37 UTCSebastian Möller Expert

Hello,

I think those are amphiboles, but could be chloritoid xls, too.

Regards,

Sebastian Möller

17th Nov 2009 12:22 UTCKnut Eldjarn 🌟 Manager

Fred,

it is hard to tell from the photo and Sebastian may also be right. Chloritoid or a related mineral would be very soft. An amphibole would have 2 pronounced cleavages at 60^o & 120^o. You should be able to test this - or the possibility of ilmenite/hematite if hard, semi-metallic, heavy and only 1 pronounced cleavage.

Knut

17th Nov 2009 16:24 UTCRonald John Gyllenhammer Expert

Hi Fred,

Knut and Sebastian make good points. If Ilmenite it may be slightly magnetic, try a very strong magnet for weak attraction. I think maybe Ferrohornblende (amphibole) or Augite (pyroxene). On this cobble you can look for a cross-section, this may display a shape as well as cleavage. As knut suggests, check the angles; amphibole 56-124 degrees, pyroxene is close to 90 degree angles of cleavage. Here's a good site that illustrates their cross-sections and cleavage. http://images.google.com/imgres?imgurl=http://www.tulane.edu/~sanelson/images/amphibole_cleavage.gif&imgrefurl=http://www.tulane.edu/~sanelson/eens211/inosilicates.htm&usg=__pQh5ymCtlk2ym8oqJDdFvQj_7EU=&h=172&w=236&sz=4&hl=en&start=2&um=1&tbnid=ZnK3kEgS03pLiM:&tbnh=79&tbnw=109&prev=/images%3Fq%3Dpyroxene%2Bamphibole%2Bcleavage%26hl%3Den%26rlz%3D1R2HPIA_enUS349%26sa%3DN%26um%3D1 If you can't find cleavage, as others suggest; try streak, hardness, etc. Good luck and all the best.

Ron

17th Nov 2009 19:53 UTCerik vercammen

Chloritoite looks a bit like chlorite (whence the name) but is much harder: 6,5 on the scale of Mohs.

This rock reminds me of the "garbenschiefer" (sheaf-schist) from the Alps: amphibole with mica(like) minerals.

18th Nov 2009 05:34 UTCFred A. Schuster

vielen Danke

thanks for the good information! I especially will use that web site Ron that is good! When I get some time I will streak test it and look at the cleavage with a macro lens. I was different than muchof the surrounding cobbles. Mostly I was looking at white quartz vein material hoping for cavities. There was a lot of white quartzpieces with somepyrite. But no keepers. this was different though.

Fred

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