matt2432
starting to spend too much on rocks
Member since December 2014
Posts: 171
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Post by matt2432 on Jan 15, 2015 21:06:24 GMT -5
Found these along the river last fall, any idea what they are? I was thinking maybe some sort of banded jasper, but I have no idea.
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Jasper?
Jan 15, 2015 21:22:39 GMT -5
Post by deb193redux on Jan 15, 2015 21:22:39 GMT -5
they don't look like they have enough silica to be jasper. can you scratch they with a piece of glass or obsidian?
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matt2432
starting to spend too much on rocks
Member since December 2014
Posts: 171
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Jasper?
Jan 15, 2015 21:27:13 GMT -5
Post by matt2432 on Jan 15, 2015 21:27:13 GMT -5
The bottom and right one are pretty hard. I don't know where exactly on the Mohs scale, but they sparked pretty good when I ground them on the tile saw. All 3 are in a course tumble right now, so we'll see how they hold up.
How can you tell how much silica they have from a picture?
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,487
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Post by Sabre52 on Jan 15, 2015 21:37:03 GMT -5
Those are identical to the banded chert varieties we find all over south Texas. Those flow lines are called Liesegang lines and are typical for the type.....Mel
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matt2432
starting to spend too much on rocks
Member since December 2014
Posts: 171
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Jasper?
Jan 15, 2015 21:51:33 GMT -5
Post by matt2432 on Jan 15, 2015 21:51:33 GMT -5
Good to know Mel, thanks for the info! Does it tumble well?
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Jasper?
Jan 15, 2015 22:06:24 GMT -5
Post by Jugglerguy on Jan 15, 2015 22:06:24 GMT -5
Chert in Michigan doesn't look that cool, but it tumbles well.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,487
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Post by Sabre52 on Jan 15, 2015 22:22:48 GMT -5
Matt, Yep, the tumble to a very glassy finish. I tumble quite a few of them and some show great bullseyes too. Like them a lot!....Mel
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Jasper?
Jan 15, 2015 22:52:43 GMT -5
Post by deb193redux on Jan 15, 2015 22:52:43 GMT -5
How can you tell how much silica they have from a picture? I was just judging by the weathering pattern and the fine veins on the surface. The very matt looking appearance. Often river tumbled jasper will show a bit of dull shine when cleaned. But if the surface is a bit oxidized those veins could be misleading. I can believe chert.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,711
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Post by Fossilman on Jan 16, 2015 10:31:36 GMT -5
Matt,glad you have them ID'ed....Keep hunting that Lake Sacajawea area,your going to find some nice goodies..........
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Jasper?
Jan 17, 2015 14:46:11 GMT -5
Post by snowmom on Jan 17, 2015 14:46:11 GMT -5
that bottom one is going to be really neat. don't forget to show us the 'after' photos to go with these!
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