dmharrisn
off to a rocking start
Member since March 2010
Posts: 14
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Post by dmharrisn on May 1, 2010 20:07:35 GMT -5
Thanks so much for the recommendation to therockshed.com Very nice prices and selection. Now, looking at it, we are not pros like you guys so tell me if these are good rocks to try together and will we get good results? moonstone, turitella agates, quartz and tiger eye. Can I get all four and toss them together? not sure of their hardness. Thanks, you guys and your advice rocks!
And is all quartz the same hardness? and agates? Are they all the same hardness?
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Post by deb193redux on May 2, 2010 0:11:46 GMT -5
There could be problems. All quartz and agate is silica, which is MOHS 7, but there are variations in density and brittleness. The more macro crystal structure of quartz can make some quartz more likely to show crazing on the edges and/or break while tumbling. But then some agates are very fractured, so ....
Some terr agate is very well silicified, with blue-white fossils in fine rootbear like agate. But some is not quite silicified fossils (i.e., some calcium carbonate still present, or hollows inside the shells), and the agate a little grainy like asphalt. IF you see that you have the latter, you should consider toss it and getting some more.
The tigereye can be fibrous. This is an asbestos-like mineral where the fibers are later silicified and/or replaced with silica. If the fibers are very well silicified (or replaced), then no problems and a nice tumble. If there is any tendency to show fibrous pitting, or to be softer in the most chatoyant areas, then there could be a problem. Good tigereye feels heavy for its size, and the chatoyant area is well bonded to the rest of the rock. Dark ice-tea like areas around the chatoyant areas fare best. Lighter tan is often soft, and bluish-gray is hematite, which is also softer but polishes well.
You might mix these for a few initial course charges. Then inspect the stones for any evidence of problems and then decide about keeping them together or separating them.
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Post by susand24224 on May 2, 2010 19:42:18 GMT -5
You got a very good answer above, but I will add that the moonstone definitely will not fare well with the mix you have given. It not only is softer, it sort of "shelves" and is very prone to breakage. Moonstone can be difficult by itself, but I doubt you would end up with much mixing it with Mohs 7 rocks.
Susan
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Post by deb193redux on May 3, 2010 11:28:37 GMT -5
Susan makes a good point about the moonstone. It is a feldspar and has cleavage planes, and when tumbling, breakage occurs along these planes, or a kind of chipping can occur when you get the thin edge of a plane. You can read a bit about them here: www.gemstone.org/gem-by-gem/english/moonstone.htmlSo in addition to the shelving Susan mentions, consider that tumbling will not systematically produce the optimal dome height and orientation for the stone that gives the famous monstone play of light. Also, the clear cabbed stones seen in pictures are hand-selected from rock that can be more cloudy and opaque. Be prepared for the moonstone not to be clear. To see what you might get, and judge if you will be satisfied, here are some threads where folks here tumbled moonstone (including with quartz). forum.rocktumblinghobby.com/index.cgi?board=trtphoto&action=display&thread=33523NatureNut gives a great photo record here: forum.rocktumblinghobby.com/index.cgi?board=trtphoto&action=display&thread=32445I had good luck polishing some pink/orange feldspar - but I cut and roughly shapped small rectangles before starting to tumble. The feldspar was also tumbled (in a Lot-O vibe) with pink quartz, terr agate, dalmation jasper, and butter jade. The results were pretty good:  A lot depends on what level of perfection you are looking for in your tumble. the batch that one person sees as having many flaws, is judged by the next person to be pretty good overall. This is why some people keep stones in the course grind until they are perfect, while others move them along with surface imperfections. Some folks discard flawed stones each time they rinse and recharge, others keep them in for the ride. |
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