matt111399
starting to shine!
Member since April 2008
Posts: 26
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Post by matt111399 on Apr 21, 2008 0:11:17 GMT -5
Close to home is a location called Garnet Hill. Almandine garnets in quartz-lined vugs in pink rhyolite are found here. Question: Anyone ever tired to put these in a rotary? The Rhyolite seems pourous so my guess is it would get chewed up easliy. Garnets are fairly tough (MOH = ?) so I guess they would survive. Looking for a way to extract the garnets - sanding and using a knife just doesn't work. Thanks in advance.
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geogoddess
spending too much on rocks
Member since December 2007
Posts: 287
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Post by geogoddess on Apr 21, 2008 1:12:21 GMT -5
I've got a bunch of garnets from that neck of the woods, from a summer school session spent there. I recently looked for mine to try to put them into the tumbler, but didn't find them. In the field I would usually just gently tap the rhyolite to bust out the garnets.
You're right, the rhyolite will probably chew up and bust off given enough time. Garnets are about a 7, so they'll polish up like agates.
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Apr 21, 2008 2:57:26 GMT -5
Garnets are pretty tough, so I suggest taking a hammer to the rhyolite to either free the garnets entirely, or at least to break the rhyolite into small enough pieces that there isn't much matrix to tumble away in order to free the garnets. Once you've got the garnets out of the matrix, they tumble up nicely. Here's some pea-size garnets from India that I put through a rotary tumbler. -Don  |
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chassroc
Cave Dweller 
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
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Post by chassroc on Apr 21, 2008 7:44:16 GMT -5
Nice tumble and shine on those Granets
csroc
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DeanW
has rocks in the head
Member since December 2007
Posts: 721
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Post by DeanW on Apr 21, 2008 13:15:00 GMT -5
I've been told that those particular garnets, I also have some, are not real good for faceting. I've sold a few as in-matrix-specimens. I hadn't thought about tumbling them - will have to try.
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geogoddess
spending too much on rocks
Member since December 2007
Posts: 287
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Post by geogoddess on Apr 21, 2008 13:18:25 GMT -5
The ones I have are all pretty small... like the ones in the picture. I would imagine they'd be pretty difficult to facet.
On the other hand, I have some out of N. Idaho/Montana that are quite large and have a great crystal structure.
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matt111399
starting to shine!
Member since April 2008
Posts: 26
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Post by matt111399 on Apr 22, 2008 1:17:18 GMT -5
Hey Dean - You're right...these garnets aren't worth much (sshhhhh, don't tell my kids). Mine all have fractures and discoloration. But, my girls think they are hot stuff when find these at the site. I'll throw a batch in soon and let you know what happens. I need a better way to chew up the matrix besides having the belt sander eat my fingers.  |
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