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Post by HankRocks on Apr 28, 2018 12:34:18 GMT -5
Included in my recent big Saw purchase were some assorted grits and polishes. The usual case where some of the containers are marked "Polish". In both cases the polish itself has a dull yellow color so I suspect it is Cerium Oxide or maybe Tripoli.
Questions;
1) Is there any way to distinguish between Cerium and Tripoli? 2) Can Cerium be used for tumbling?, and any particular type of rock? 3) How about Chrome-Oxide uses. The book says Jade, Lapis and Rhodonite, anything else?. 4) I assume Tripoli can be used as a pre-polish, correct?
Thanks Henry
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Post by manofglass on Apr 28, 2018 12:40:13 GMT -5
Do a search on Covington’s website They have photos of there polish
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Post by rmf on Apr 28, 2018 13:11:12 GMT -5
I have a customer that uses tripoli to polish tumbled agates and jaspers. Yes Cerium is a good tumbler polish as well. Cerium tends to be pinkish to a pinkish brown where tripoli tends to be white to a yellowish brown. I have some chrome oxide and have never used it. It is a nice green color and is very messy
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nchillbilly
starting to spend too much on rocks
Member since January 2018
Posts: 212
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Post by nchillbilly on Apr 28, 2018 13:29:14 GMT -5
I think I read on here somewhere that cerium oxide was good for obsidian. I have never tried it on obsidian because I've had good success with 14000 a/o.
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Post by pauls on Apr 28, 2018 16:02:58 GMT -5
Cerium is great stuff for the softer 5 to 6 mohs rocks, at least for cabs, I have never tried in in a tumbler. Tripoli is a good metal polish but no good for rocks, it's ground limestone and diatomaceous earth mixture. Don't you just love those mystery tins labeled polish.
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Post by taylor on Apr 28, 2018 16:23:32 GMT -5
Cerium oxide works great for us in our rotary tumblers. We run hard loads and soft loads. Hard stuff includes various agates, flint, mookaite, and banded iron. Soft stuff includes various slag glasses, obsidian, onyx and marble.
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Apr 28, 2018 19:50:16 GMT -5
Cerium is great stuff for the softer 5 to 6 mohs rocks, at least for cabs, I have never tried in in a tumbler. Tripoli is a good metal polish but no good for rocks, it's ground limestone and diatomaceous earth mixture. Don't you just love those mystery tins labeled polish. Indeed...works pretty good on 4 to 5Mohs as well (I only vibe after 1st stage grind a polish stages)....used it on a batch of Sphalerite quartz imbedded material recently, after the pre-polish AO. Surprisingly, the stuff got a nice gloss.....not deep, but slippery shiny finish.
Note:
A little tricky to establish a creamy slurry....not for a novice.....sensitive to "soaps", as in needs to stick, not slide like soap applications tend to provide.
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Post by rmf on Apr 28, 2018 20:40:14 GMT -5
From: www.britannica.com/science/tripoli-rockTripoli, porous, friable, microcrystalline siliceous rock of sedimentary origin that is composed chiefly of chalcedony and microcrystalline quartz. Although the name tripoli was chosen because of the rock’s superficial resemblance to tripolite, a diatomite or from Tripolitania region, Libya, the term does not include diatomite, or hardened diatomaceous earth. Some tripoli is a coherent residuum from leached limestone, dolomite, or chert; other examples probably are colloidal silica that has been leached from other rocks and earth, gathered together in lumps, and partly recrystallized. The friable variety is more typical. The chemical composition is usually more than 95 percent silica (silicon dioxide, SiO2), but the impurities may impart desirable physical properties.
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