Dalmatian Stone: aka "Dalmatian Jasper"
This image shows a 4-pound bag of dalmatian stone tumbling rough, dumped into a colander and sprayed with water to reveal its full color. Click on the image for a larger view.
Dalmatian Stone Tumbling and Cabbing Rough
Size: mostly 3/4 to 1 3/4 inch pieces
Dalmatian Stone (also known as "dalmatian jasper") is a black and white igneous rock mined in Chihuahua, Mexico. It is a favorite tumbling rough of people who are new to the rock tumbling hobby. Why? It quickly develops a nice rounded shape in the tumbler and polishes to a soft glow. It makes success easy. And, the tumbled stones are a novelty because of their name and appearance.
Here's an example of what Dalmatian Stone looks like when it has been tumble-polished in a rotary tumbler. The stones round nicely and the polish is more of a "soft glow" instead of the "bright glassy" polish that develops on pieces of agate and quartz.
The Dalmatian Stone that we are selling is mostly in 3/4" to 1 3/4" pieces. The four pound bags might have a few smaller pieces and a few larger pieces. That is expected when buying bulk rough. The background color of dalmatian stone can range from a light brown to a bright white. We like the material that we are selling because the density of the black spots is just right to deserve the "dalmatian" name. There are not too many and not too few.
When this material first hit the lapidary market almost everyone called it "Dalmatian Jasper." It looks like the breed of large white dog with black spots. The name was easy to remember and it stuck. It really stuck. Nobody had trouble remembering the name - even after hearing it only once. Some people will guess the name if you ask them to try. The problem -- this stuff isn't "jasper."
What Is Dalmatian Stone?
Dalmatian stone is not a jasper. It is an igneous rock composed of white albite (a feldspar mineral) and black arfvedsonite (a mineral similar to hornblende). Arf! Some specimens might contain similar but closely related feldspar and amphibole minerals. Dalmatian stone shapes nicely in a rock tumbler in minimal time because it is softer than the agate, quartz and jasper that most people are used to tumbling. The minerals in dalmatian stone have a Mohs hardness of about 6, while quartz, agate and jasper have a hardness of 7.
If you want to know more about Dalmatian Stone we have information about it and its lab analysis here.
How to Tumble Dalmatian Stone
Dalmatian Stone can be tumbled in either a rotary tumbler or a vibratory tumbler. We often run the coarse step in rotary to round the stones and then do medium, fine and polish in a vibratory tumbler for faster production. Here's what you need to know before you get started.
1) Dalmatian Stone is softer than the rocks for which most tumbling instructions are written. It will round nicely in a shorter amount of time than agate, jasper, quartz and the silicified varieties of petrified wood. So, your tumbling time can be slightly reduced. Tumbling too long isn't a problem - but it will reduce the size of your tumbled stones and run up your electric bill. We reduce our tumbling time slightly as explained in the rotary and vibratory suggestions below.
2) Dalmatian Stone easily accepts a polish with TXP aluminum oxide. However, the polish is a soft glow rather than the mirror bright polish that you can produce on materials like agate and obsidian.
Rotary Tumbler Suggestions:
Step 1: Fill the barrel 2/3 full of Dalmatian Stone with enough small ceramic media or small-size rough to fill the spaces between the stones. This suggestion is given here because the pieces we are selling are 3/4 to 1 3/4 inch in size and small material will be needed to produce nicely shaped stones that are smoothed on all sides. Then add two level tablespoons of coarse rock tumbler grit for each pound of material in your tumbler barrel (rocks and media), then add enough water so that just the tips of the rocks are not covered. Tumble for ten to fifteen days.
Step 2 and Step 3: After cleaning the rocks and barrel, place the rocks and media back into the barrel, then add 2 level teaspoons of medium or fine grit, depending upon your step in the rock tumbling process. Finally, add enough water to almost cover the rocks and tumble for five or six days.
Step 4: This is the polishing step. We use 2 level tablespoons of of TXP polish per pound of stones and media. Then we tumble for seven days. Other polishes, such as tin oxide and cerium oxide will work, but we use TXP because it costs less and does just as good of a job. Burnish for one hour if needed.
Vibratory Tumbler Suggestions:
Step 1: Fill the vibratory bowl to the level recommended by the manufacturer with a mixture of Dalmatian Stone and ceramic media or small rough. Add enough small-size rough or ceramic media to fill the spaces between the pieces of Dalmatian Stone. Then add 1/2 tablespoon of medium grit for each pound of material in the tumbler bowl. Then start the tumbler and add a small amount of water - enough to make the grit stick to the rough. Run until the rough has been smoothed on all sides, rinsing the mud from the rough and adding fresh grit every 24 hours.
Dalmatian Stone is soft compared to most other tumbling roughs. It will shape quickly and made lots of mud. Check your tumbler frequently and add enough water to maintain a thin mud.
Step 2: Thoroughly clean the rough and media from Step 1. Place them back into the tumbler bowl and add 1/2 tablespoon of medium grit for each pound of material in the bowl. Then add enough water for proper tumbling and tumble for 24 to 36 hours. There is no need to refresh the grit. Clean the rough and media and you are ready for the polishing step.
Step 3: We recommend TXP aluminum oxide polish for Dalmatian Stone. Add 1/2 tablespoon per pound of material in the bowl then start the tumbler and add enough water to form a thin milky slurry. It will only take a few tablespoons. Then tumble, checking every 12 hours, add water if needed, until the Dalmatian Stone has a soft glowing polish. Burnish for 30 minutes if needed.
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