Rock Crystal (Clear Quartz)- Rock Tumbler Rough
This image shows a 3-pound bag of rock crystal tumbling rough, dumped into a colander and sprayed with water - just as we do with every other rough. Click on the image for a larger view. This is transparent colorless quartz and the photo does not do this wonderful material justice.
Rock Crystal Tumbling Rough
Size: mostly 1 to 2 1/2 inch pieces
What Is "Rock Crystal"?
"Rock Crystal" is a popular name for a colorless quartz that is clear enough that you can see thorugh it. It is rarely seen as a tumbling rough and we have a small quantity that we are offering for sale. It is in large chunky pieces that range between about 1 and 2 1/2 inches in size.
This photo shows how nice our rock crystal rough shapes and polishes following the tumbling recipe below.
ADVANCED Rock Tumbling Recipe:
Rock Crystal (1 to 2 1/2 inches)
As a crystalline variety of quartz, rock crystal can be polished to a very high luster but many people who tumble it in pieces over about one inch in size experience a problem - tiny bruises around the edges of their tumbled stones. These bruises are caused by quartz-to-quartz impacts within the tumbler barrel. This problem is easy to solve by tumbling the quartz in a sea of ceramic cylinder media. The small particles of ceramic media smooth the tumbling action, and, isolate the pieces of quartz from impact with one another. The ceramic media absorbs much of the impact energy produced during the tumble. When tumbling the rock crystal sold here two things should be considered:
1) More Time: Crystalline quartz is hard and because of that it requires more time in the tumbler with coarse grit to produce nicely-shaped tumbled stones. For the rough that we are selling, in six-, twelve- and fifteen-pound capacity barrels, two to four weeks might be required to shape the rough nicely. In small tumblers of two or three pounds capacity, three or four weeks - or longer - can be needed. We suggest tumbling crystalline quartz in coarse grit for two weeks, clean the rough and the barrel, then run one or two more weeks in coarse grit - until you are happy with the shape. When you are happy with the shape, move on to medium grit.
2) Media Needed: You want crystalline quartz to be swimming in a sea of ceramic cylinder media. This is required if you want to avoid bruised tumbled stones. When we tumble crystalline quartz in coarse grit, we fill the barrel about a third of the way with ceramic cylinders and then add the quartz. That will give you a ratio of about 70% quartz and 30% ceramics. The cylindrical shape of the ceramic media will act like a roller bearing and give the rocks a smooth tumbling action in the barrel. The small pieces of media also deliver grit to all surfaces of the rough.
|Using Small-Size Rough Instead of Media: Some people use small pieces of rough instead of media. This can work well if your small rough meets two requirements: 1) the small pieces of rough must be blocky or rounded in shape to produce a good tumbling action - thin or flaky pieces will break up quickly and might not produce a smooth tumbling action; 2) the small pieces of rough must have a hardness that is equal to or greater than the rough that they are tumbled with - if they are softer they will tumble into mud before their job has been done.|
Recipe for Rotary Tumbling:
Barrel slurry dumped down the drain will harden like concrete.
Coarse Grit Step: Fill the barrel 2/3 full with a mix of 20-30% media and 70-80% rock crystal. Add two level tablespoons of coarse grit per pound of material and cover the rocks completely with water. Then tumble for two to four weeks - or long enough to shape and smooth the stones.
Medium Grit and Fine Grit Steps: Again, fill the barrel 2/3 full. Your rough volume will have dropped because of loss during the coarse and medium grit steps. Add some additional media to bring the barrel up to proper level. This should get the media up to the suggested 40-50% of barrel capacity. Use two level tablespoons of grit per pound of material for each of these steps. Add enough water to almost cover the rocks and tumble for one week. Don't over-tumble at this step. If you allow the rocks to tumble more than is needed, you run the risk of bruising.
Polish Step: Be sure that the rocks, media, barrel and lid are extra clean. Also, make sure that the barrel is filled to the proper level. Add more media if needed, but if you have to add more media be sure it is clean POLISHED media. Dusty media or media that has not been broken in and smoothed can scratch up your tumbled stones at this step. We use two level tablespoons of TXP aluminum polish for each pound of rock. Add water until it almost covers the rocks, and tumble for one week.
Burnish If Needed: This material usually takes a great polish. However, burnishing it after the polish step can often improve the look of the stones. If you would like to try burnishing, full instructions can be found here.
Vibratory Tumbler Suggestions:
Step 1: We fill the vibratory tumbler to the fullest capacity recommended by the manufacturer. If you fail to do that, the tumbling action will be too vigorous for crystalline quartz, and bruising will probably occur. Do this for every step of your tumbling with crystalline quartz. We use 1/2 tablespoon of medium grit per pound of material in the bowl. We also add just enough water to make the grit stick to the rough at the start, then as tumbling progresses we add water to maintain a thin muddy slurry. We rinse the rough and add fresh grit and water every 48 hours or as needed. Tumble for as many days as are needed to smooth the surfaces of the rocks. Don't overtumble or bruising will occur.
Step 2: We use fine grit for this step and tumble two days. We use 1/2 tablespoon of grit for each pound of material in the bowl. Start with just enough water to make the grit stick to the rock and tumble for two days, checking often to be sure that the moisture content is right. Your volume probably dropped during Step 1, so you should add enough ceramic media to bring your bowl up to proper operating level. This media should be broken in and free of factory edges.
Step 3: We use TXP aluminum oxide polish, but many people use #61 Rapid Polish for almost all of their vibratory tumbling. Tumble for two days in polish. Check frequently to be sure that your moisture level is right and to monitor the progress of the polishing. Expect it to take two days, but stop if you achieve a great polish in a shorter amount of time or go a little longer if you think it will improve the polish. Too much polishing will produce bruises on crystalline quartz. Burnish for 30 minutes in soapy water if needed.
Polished Rock Crystal
If you would rather just purchase tumbled stones of this material. We usually have medium-size tumbled Rock Crystal here.
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