jr
off to a rocking start
Member since July 2013
Posts: 3
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Post by jr on Jul 11, 2013 22:17:53 GMT -5
I've been given some beach dallasite tumbled by someone else. Don't know who, don't know when, don't know what grits or times, but there's a pretty high gloss on it. Problem is, it's very grey. If I compare the colors in other polished dallasite, this stuff looks like it is still on the beach in bright sunlight. The black isn't black. What went wrong? And how do I fix it? I suspect it's been tumbled insufficiently long with 220 grit, or else the wrong finishing powder was used, but I'm a novice and I don't know.
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jr
off to a rocking start
Member since July 2013
Posts: 3
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Post by jr on Jul 11, 2013 22:20:26 GMT -5
PS: the previous tumbler also tumbled a few other rocks he mistook for dallasite. They've all gone grey.
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Post by connrock on Jul 12, 2013 8:31:25 GMT -5
I'm taking a wild guess without seeing the dallasite but sometimes rocks have a grayish "haze" on them after polishing.In may cases a burnishing run will clear that haze up. Good luck,,,
connrock
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Post by Drummond Island Rocks on Jul 12, 2013 8:56:47 GMT -5
posting pictures will get you more specific answers but sometimes "frosting" will grey out some softer materials. Frosting happens when soft materials rub on each other in the tumbler and the rocks are actually grinding each other and the grits and polish cant stop that. The only way to protect for "frosting" is to try a mix of 50% ceramic or plastic filler and %50 of the rock. The filler minimizes the contact between the rocks. I did find this information from a club website in Victoria B.C.. Its their club stone so I bet if you contact them they can help you with tumbling instructions. www.islandnet.com/~vlms/clubinfo.htmlVLMS Club Stone - Dallasite
Dallasite is the Victoria Lapidary and Mineral Society’s club stone. The rock is so named because the first identified pieces of it were found along Dallas Road in Victoria. This is of interest as the material would have had to travel a fair distance from the source. There are occurrences along the east side of Vancouver Island and some sizable deposits in the Alberni Area.
The material is a volcanic breccia consisting of green and black material in a white base which also forms the VLMS club colours. The size of the green and black material varies and it can form some very attractive patterns. It is believed to form as pillow lava underwater and through geological uplift become deposits on land.
Working Dallasite can be challenging as there is a variation in the hardness of the different areas of the material as well as the usual cracks and crevices. When tumbling it is best to only have Dallasite in the load.
When cutting cabochons it is best to stick to diamond based wheels such as on a Genie – and do a final polish with tin oxide. This will avoid undercutting the softer areas.
Good places to collect include Island View Beach, beaches around Parksville and of course beaches around Victoria. Look for cobble beaches and the predominate white to guide you. Pieces occur in size from a pebble up to good size (5 lbs – 2 kg) boulders Chuck
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jr
off to a rocking start
Member since July 2013
Posts: 3
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Post by jr on Jul 14, 2013 13:33:03 GMT -5
Thanks, people! Guess I'll tumble that load myself and see what happens in light of your comments. At the moment I'm researching the best way to tumble dallasite, but I'm sure I can do better than this.
I'm guessing that tumbling stones that combine materials of different hardnesses, there shouldn't be too much variation in the size of pebbles in the load. If I include small pebbles, maybe the quartz in them (quartz is in most dallasite) would wear away the softer materials in larger stones more than desirable?
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