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How to Polish Chlorastrolite

Known colloquially as Greenstone, Chlorastrolite is a hard, green mineral often found in the Upper Peninsula of Michigan. Polishing this stone requires a delicate hand, as the inner structure of the stone is often hollow or filled with brittle calcite. Typically a five or six on the Mohs' hardness scale, polishing the stone to perfection can be time consuming, yet rewarding.

Things You'll Need

Rock tumbler
Polishing disk
Spray bottle
Flex shaft tool
Chlorastrolite

Instructions

- 1
  Choose a piece of rough chlorastrolite to polish. Select a piece that does not have any cracks or holes, as only the outer shell contains the pattern of the stone.
- 2
  Place the chlorastrolite in the tumbler until the edges are dulled and the stone has a defined shape.
- 3
  Use the polishing disk to continue polishing until the entire stone is smooth and round. Change to finer grit polishing disks as the polishing progresses. Spray the disks with water. Use care to only polish the outer shell and not to crack into the hollow centers.

Rocks & Minerals