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Apache Tears (Obsidian Nodules) Tumbler Rough
Apache Tears (Black Obsidian)
Apache tears are small roundish nodules of black volcanic glass known as "obsidian".
They look opaque in the image above but when polished most of them will be translucent to semi-transparent if you hold them up to the light. They make beautiful jet black tumbled stones. You can see a photo of Apache Tears that we tumbled below. We also have polished Apache Tears for sale here.
The Apache Tears for sale here range in size from approximately 1/4" (6 mm) to 1 1/2"" (38 mm) in diameter.
Lots of people say that Apache Tears, various types of obsidian, and other natural glasses are a challenge to
polish. The problem that they encounter is brusing and chipping if the tears are tossed
around too vigorously in a rotary tumbler.
That problem is easy to solve!
Simply load the Apache Tears into a tumbler barrel with about 30% to 50% (by volume)
small ceramic cylinders. The barrel should be loaded to about 3/4 full. The small ceramic pellets
will cushion the Apache tears as they tumble and prevent hard impacts in the barrel.
That's how you prevent brusing and chipping.
We have successfully polished Apache tears in a rotary tumbler with
small ceramic cylinders and TXP polish using the four step tumbling method (a few days in coarse grit, one week in medium grit, one week in fine grit, and one week in polish). Our favorite way to polish them is described at the bottom of this page.
Here are two more tips about tumbling Apache Tears and obsidian in general.....
First, obsidian is a lot softer than the agates and jaspers
that most people tumble. They are 5.5 on the Mohs Hardness Scale while jasper and agate are 7. If you tumble
Apache Tears with agate and jasper they will wear away while the agate and jasper are still being rounded. Apache Tears
should be tumbled separately.
Second, instead of allowing them to tumble a week in coarse grit it is best to
check on them after four to five days. Apache Tears have a hardness of 5.5 but the silicon
carbide has a hardness of 9+. The tears will wear away rapidly in the hard silicon carbide.
You don't want to open your tumbler and discover that your tears have tumbled to the size if small peas!
This photo is of a batch of Apache Tears that we polished. Look at that bright polish and no brusing! Here's how we did it......
We loaded about two pounds of Apache Tears and about two pounds of small ceramic cylinders into the barrel of a Lortone QT6 tumbler with 60/90
grit silicon carbide. We then tumbled for seven days. The Apache Tears that we tumbled were already rounded. In addition,
they are a lot softer than agates and jaspers - so seven days in coarse grit was enough to produce nice rounded shapes with
almost all of the dimples smoothed out.
We loaded the Apache Tears and the small ceramic cylinders into a single barrel
Lot-O-Tumbler and ran them for 48 hours in
150/220 grit, rinsing and adding new grit after
the first 24 hours.
Step 3: We then ran the Apache Tears and ceramic cylinders for 24 hours in the
Lot-O-Tumbler with 500F grit prepolish. The tears
were now showing a slight gloss.
Step 4: The final step was 48 hours in the Lot-O-Tumbler with
TXP aluminum oxide polish. We checked the tears
at the end of 24 hours and they had a bright polish but it wasn't mirror smooth throughout. So
we added one Lot-o-Tumbler cap full of water and allowed the tumbler to run another 24 hours.
Wow! They came out great! Total processing time was one week and five days.
||Large Ceramic Media:
Large ceramic pellets work great as a filler and for delivering grit or polish to difficult-to-reach surfaces. More information...
||Small Ceramic Media:
Small ceramic pellets work great when you need small material for better tumbling action or to deliver grit or polish to difficult-to-reach surfaces. More information...
Use plastic pellets to cushion fragile stones when tumbling in a rotary tumbler. More information...
| Rock Tumblers and Supplies
||We highly recommend:
Modern Rock Tumbling by Steve Hart.
Learning is the fastest way to improve the quality of
rocks that you tumble. In this book you will learn from an expert with extensive
experience. You will increase your abilities, learn to save time, money and have a great reference book
that you will use again and again.
||We highly recommend:
Gemstones of the World (fifth edition) by Walter Schumann.
One of the most popular gemstone books ever written, with over one million copies sold. It has about 100 pages of basic gemstone information and about 200 pages dedicated to photos and descriptions of over 100 gems and gem materials.
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