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Lake Superior Agate Tumbler Rough

Lake Superior Agate tumbling rough
This is a photograph of our Lake Superior Agate rough on the left and what it looks like polished on the right. This material consists of agate nodules and pieces between 1/4" and 1 1/4" in diameter. Lots of red, white, gray, orange, brown and crystal color material with nice banding and occasional eyes.
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Two Pounds
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Lake Superior Agate

Size: mostly 1/4 to 1 1/4 inch pieces

Lake Superior Agate is widely known as a tumbling rough. It is so popular in the Great Lakes area that the Minnesota legislature designated it as the official "state gemstone".

Lake Superior Agate is typically a banded material - often concentric - but sometimes has eyes and mossy patterns. The red, yellow, orange and brown colors are a result of an iron pigment within the agate material.

Our Lake Superior Agate mix consists of small nodules and nodule fragments found in the Great Lakes area. It is a tough, dense material in pieces that range from approximately 1/4" (6 mm) to 1 1/4"" (32 mm) in size. It takes a great polish. We use TXP polish - an aluminum oxide compound - when we polish Lake Superior Agate.

A photo of some finished Lake Superior Agate that we polished is shown below.
Polished Lake Superior Agate
This photo is of a batch of Lake Superior Agate rough that we polished. It is a very hard material that can take an absolutely brilliant polish. Our tumbles had plenty of bands, quite a few eyes, a little moss, several crystal windows and lots of red, orange and brown colors. Here are the steps that we used to achieve this polish.

Steps 1A, 1B, 1C: We loaded a little over four pounds of rough into the barrel of a Lortone QT6 tumbler with 60/90 grit silicon carbide and tumbled for three weeks. The nodules had some rough husks and the broken pieces had some deep dimples so we knew that we would run more than one week in 60/90 grit to get the really nicely rounded tumbles that we like to produce. At the end of Week One we rinsed the nodules, picked out a few that revealed cracks or porosity and loaded the rest back into the barrel with fresh 60/90 grit. At the end of Week Two we rinsed and reloaded with fresh 60/90 grit and ran for Week Three. That's three weeks total in coarse (60/90) grit.

Step 2: We loaded the agates into a single barrel Lot-O-Tumbler and ran for two days with 150/220 grit, rinsing and adding new grit every 24 hours.

Step 3: We then ran two days in the Lot-O-Tumbler with 500F grit prepolish, rinsing and adding fresh grit after 24 hours.

Step 4: The final step was just 24 hours in the Lot-O-Tumbler with TXP aluminum oxide polish. Burnishing was not needed. Wow! We were amazed at how brightly they polished in just one day.

Total processing time was three weeks, five days.

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1 pound of each: coarse, medium and fine grit. 8 ounces of TXP polish. This is enough supplies to tumble up to four three-pound barrels of rocks. Save money with a large grit kit.