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Post by tkrueger3 on Mar 2, 2011 11:41:01 GMT -5
I found this rock in one of my flower beds. I thought it might be some form of obsidian, and I was pleased. Then I cut it. YUCK! It turned everything inside the saw a gritty black! NASTY! It's not obsidian, I think - I've never had obsidian change the color of the oil. But what is it? Pure lava rock? It contains almost imperceptible veins of red, like rust, running through it, while the cut surface seems to reflect a very faint "brecciated", but monotonal black pattern. It seems to "feel" heavy in my hand - I haven't weighed it, but it feels about the same weight as would an equal sized quartz or jasper rock. The outer surface appears to me have been formed by heat, rather than by erosion, leading me to believe it could be lava. Any experts, please set me straight! I wouldn't mind slicing and dicing this thing if it wasn't just so darned messy! Thanks, Tom
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Post by NatureNut on Mar 2, 2011 11:59:36 GMT -5
Okay, this is a complete Hail Mary guess, but could it be Hematite? With a little Red Jasper running through? Kind of a Jaspellite that's super heavy on the Hematite. Jo
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Post by drocknut on Mar 2, 2011 12:30:05 GMT -5
That would be my thinking too Jo, seems like hematite to me too. If it leaves a brown streak on a white piece of paper or better yet a streak plate, then it's more than likely hematite. Hope that helps.
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Post by Hard Rock Cafe on Mar 2, 2011 13:26:10 GMT -5
The weight, color, and rusty veins are consistent with hematite, but hematite normally turns oil red, not black, and it's usually not gritty. It's too fine grained to be basalt.
Maybe it's hematite with enough impurities to color the oil black? Chuck
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MikeS
fully equipped rock polisher
Member since January 2009
Posts: 1,081
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Post by MikeS on Mar 2, 2011 14:48:57 GMT -5
I'd guess hematite
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,463
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Post by Sabre52 on Mar 2, 2011 22:01:26 GMT -5
Yeah, from the look I'd have said hematite but hematite stains your oil red. Black is usually manganese in some form or another....Mel
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Jason
starting to spend too much on rocks
Member since March 2009
Posts: 216
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Post by Jason on Mar 4, 2011 10:00:15 GMT -5
hmmm..feels heavy would make me also lean towards hematite. Lava would not have that perceptible feeling of weight you describe
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carloscinco
fully equipped rock polisher
Member since July 2008
Posts: 1,639
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Post by carloscinco on Mar 10, 2011 12:37:24 GMT -5
Magnetite?
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Post by akansan on Mar 17, 2011 15:31:56 GMT -5
I would find that fairly frequently on BLM land in New Mexico - and I can't for the life of me remember what I was told it was. It was a form of Manganese, though. The stuff in NM wasn't magnetic, so I vetoed magnetite.
The breccia pattern you're seeing almost looks like fractures and oil absorption patterns. I'd be curious if it would show the same patterns if cut with water instead of oil?
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ernie
off to a rocking start
Member since April 2010
Posts: 10
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Post by ernie on Mar 24, 2011 23:31:06 GMT -5
i have this same stuff and wondered what it was as well. i was kinda pissed when i cut it open LOL so, hematite huh, what can we do with hematite?
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Post by johnjsgems on Mar 25, 2011 7:05:58 GMT -5
You can enjoy having some actual hematite. All the "magnetic hematite" used in junk jewelry is man made (or child made) in China. It has a metallic look in jewelry but is non magnetic. Psilomelane would be most common form of manganese. Most metallic rocks will feel much heavier than an agate.
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