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 auscarver and his Nephrite Jade/Imperial Rhodonite Cab!

 www.lapidaryforum.net

Another cabochon contest coming soon!

Pages: [1]   Go Down

Author Topic: Obsidian Troubles  (Read 592 times)

0 Members and 1 Guest are viewing this topic.

Shifter55

  • Newbie
  • *
  • Offline Offline
  • Posts: 23
Obsidian Troubles
« on: April 16, 2020, 02:03:18 AM »

While working with some velvet obsidian I ran into some cutting issues: grinding with my 600 mesh lap caused these spherical delaminations to suddenly appear.

These weren't in the material to begin with, I'ld feel a slight change in friction and would be about 3/4 through cutting into one of these orbs despite there being no evidence of it below the surface of the stone.
I've heard of (and experienced :angry:)obsidian fracturing on saws due to internal strain but this is seems very different to that.
Has anyone else had this issue, and what can I do to prevent it?
Logged


Felicia

  • Full Member
  • ***
  • Offline Offline
  • Posts: 237
Re: Obsidian Troubles
« Reply #1 on: April 16, 2020, 07:21:08 PM »

Don't know, small mineral bit present in the stone?? Never saw that before.
Logged

Kaljaia

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 767
Re: Obsidian Troubles
« Reply #2 on: April 17, 2020, 10:36:53 AM »

Hm. that does seem odd, maybe a perlite crystobalite? I don't know if I'm spelling that correctly. A ball of spherical crystallization inside the glass that's only showing up once air or liquid gets into it?
Logged
- Erika

I rock hunt in the Antelope/Ashwood area of the John Day river basin in Oregon.

irockhound

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1068
    • RockhoundingUSA
Re: Obsidian Troubles
« Reply #3 on: April 17, 2020, 11:10:59 AM »

That was my best guess too.  I was thinking Crystobalite but the Spherule didn't make sense but I think you are right.
Logged

Shifter55

  • Newbie
  • *
  • Offline Offline
  • Posts: 23
Re: Obsidian Troubles
« Reply #4 on: April 17, 2020, 07:25:34 PM »

Hm. that does seem odd, maybe a perlite crystobalite? I don't know if I'm spelling that correctly. A ball of spherical crystallization inside the glass that's only showing up once air or liquid gets into it?
The shape and structure of christobalites seems to be a match, though these have a darker core that seems to be less porous!
Looking over the rough surface of this piece, I've found a pocket with a white residue that might be a worn-down christobalite, originally I though it was just a bubble with dirt washed in.
Logged
Pages: [1]   Go Up
 

Page created in 0.111 seconds with 36 queries.