Applying to join this forum, you HAVE to activate your membership in YOUR email in the notice you recieve after completing application process. No activation on your part, no membership.

Lapidaryforum.net

Please login or register.

Login with username, password and session length
Advanced search  

News:

Welcome new members & old from the Lapidary/Gemstone Community Forum. Please join up. You will be approved after spam check & you must manually activate your acct with the link in your email

Congratulations to Bobby1 and his Brazilian Agate Cab!

 www.lapidaryforum.net

Another cabochon contest coming soon!

Pages: [1]   Go Down

Author Topic: How to prepare and cut chlorastrolite?  (Read 3327 times)

0 Members and 1 Guest are viewing this topic.

R.U. Sirius

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 305
  • asleep at the grinding wheel
How to prepare and cut chlorastrolite?
« on: January 26, 2024, 05:10:33 PM »

I've found this large piece of Michigan "greenstone" - a basaltic matrix with many obvious small nodules of chatoyant chlorastrolite.

I would like to try making small cabochons, but I am not sure how to approach it.

First off, how do I free a nodule from the matrix? Do I chip off with a hammer? Do I grind? Do I leave some of the matrix on the cab, or it doesn't polish at all (feels very gritty) and I should aim for clean nodules only?

Next, exposed nodules seem to be all hollow, with botryoidal turtleback inside surface. Do I make this cavity the back of the cab, and work the convex outside surface? Or should I look for solid nodules to work on?

If you've ever successfully cut this material, please share your insights.
Logged

lithicbeads

  • Administrator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3236
Re: How to prepare and cut chlorastrolite?
« Reply #1 on: January 28, 2024, 08:01:14 PM »

Greenstone , metamorphosed basalt, can get quite soft. If it hasn't been filled with silica I find it to be about as hard as feldspar .I think you should try leaving your crystal pocket in the matrix and cut the stone gently avoiding extra course diamond. I wonder if oil will harm the pocket content. Careful sanding with nova wheels or the equivalent  should be sfe  and the matrix may only take a matte finish but your pocket contents may polish at 8 or 14 thousand diamond.
Logged
Pages: [1]   Go Up
 

Page created in 0.027 seconds with 23 queries.