Kambamba Jasper - Rock Tumbler Rough
This image shows a 3-pound bag of kambamba jasper tumbling rough, dumped into a colander and sprayed with water to reveal its full color. Click on the image for a larger view.
Kambamba Jasper Tumbling Rough
Size: mostly 1 to 2 inch pieces
What is Kambamba Jasper?
Kambamba Jasper is a green tumbling rough marked with black circles and swirls that is mined in Madagascar. It produces tumbled stones with spectacular "eyes" and "orbs". Some people believe that it is a fossilized stromatolite (structures built by sediment-trapping algae) but experienced paleontologists do not accept that theory for its formation. Kambamba does not have the proper pattern of growth lines almost universally seen in stromatolite fossils.
These pieces of Kambamba Jasper are large enough to beautifully display its orbicular markings. They are also highly silicified. That makes them shape nicely in a rotary or vibratory tumbler and polish to a high luster with TXP aluminum oxide polish.
Many people who see Kambamba for the first time confuse it with "nebulae stone" -- which is an igneous rock, an orbicular granite. Other people confuse it with "ocean jasper" which is another orbicular lapidary material also found in Madagascar. (Madagascar is a large island in the Indian Ocean, off the east coast of Africa). People let them imaginations run wild with strange rocks like Kambamba.
Kambamba is Easy to Polish in a Rotary Tumbler
We use the standard four-step tumbling process in rotary, with the addition of small ceramic media. For Step 1, we fill the barrel about 2/3 full of Kambamba and then add small ceramic media and gently shake it down into the spaces between the Kambamba. We then add two tablespoons of coarse grit for each pound of jasper and media, almost cover the contents of the barrel with water and tumble for two to three weeks. That should be long enough to give your stones a nice rounded shape.
For Steps 2, 3, and 4 we use medium grit, fine grit and TXP aluminum oxide polish in sequence for one week each. For each of these we use two tablespoons per pound of rock and media. We also use enough water to almost cover the rock and media for each of these steps. We rinse the ceramic media with the rough and keep it with the rough for each step of the tumbling. Burnish if needed. In five or six weeks you should have some nice green tumbled stones with awesome black circular markings.
Vibratory Tumbling and Polishing Suggestions
In a vibratory tumbler we begin with medium grit and run until we are happy with the shape of the stones. Then we use fine grit followed by either TXP aluminum oxide polish or #61 Rapid Polish. Because this rough is in 1" to 2" pieces, we start tumbling in Step 1 with about 30% small or large ceramic media and keep the media with the rough through all steps of tumbling.
Polished Kambamba Jasper
If you would rather just purchase tumbled stones of this material. We usually have medium-size tumbled Kambamba Jasper here.
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