when buying rough gems...

[cofor]

If you by host mean the matrix, it is chalcedony of some kind. The crystals have been growing hydrothermally in former gas cavities in volcanic rock.

To relate to the first post in this thread:
To be able to buy for example diamond rough, you need years of experience and guidance from someone already in the trade. If you know almost nothing of what to look for in rough and even less about cutting, my advice is the same as from other participants around here, stay away from it. To be able to judge rough (diamonds or colored stones alike) you have to be familiar with cutting- as well as appraisal techniques. One of the main objectives when buying rough is to be able to calculate yield and quality which is difficult in colored stones and even more so in diamonds as for example twinned stones are harder (more labouring) to cut and then you have to count in the higher cutting cost.

 

[Pandora II]

Date: 1/11/2009 1:08:07 PM
Author: rparker1998

DH and I picked this up on vacation but I don''t recall I were, and I think it''s quartz...picture of the host rock to follow in next photo

I have a very similar looking piece that is made up of amethyst crystals.

 

[diagem]

Date: 1/10/2009 5:53:09 PM
Author: tourmaline_lover

Date: 1/10/2009 3:57:47 PM
Author: Pandora II
De Beers in London had a whole range of jewellery set with rough diamonds last Spring. They were all fairly vile - the poor SA tried very hard to be nice about them and then gave me the look that said ''you think they''re vile and I totally agree, but I can''t say it out loud''!

My tutor has a lovely chunk of kimberlite with a really good octohedron set in it - very nice collection piece.

I''ve seen some of the new ''organic looks'' with rough diamonds, and they''re hideous. They look like something Wilma Flintstone would wear.

That being said, some crystal formations are very beautiful and part of nature''s work of art. I know people that love benitoite crystals (they''re very beautiful) and they collect them since they''re often times much more beautiful uncut than cut.

Nature''s beauty:

 

[diagem]

Date: 1/11/2009 4:18:38 PM
Author: DiaGem

Date: 1/10/2009 5:53:09 PM
Author: tourmaline_lover

Date: 1/10/2009 3:57:47 PM
Author: Pandora II
De Beers in London had a whole range of jewellery set with rough diamonds last Spring. They were all fairly vile - the poor SA tried very hard to be nice about them and then gave me the look that said ''you think they''re vile and I totally agree, but I can''t say it out loud''!

My tutor has a lovely chunk of kimberlite with a really good octohedron set in it - very nice collection piece.

I''ve seen some of the new ''organic looks'' with rough diamonds, and they''re hideous. They look like something Wilma Flintstone would wear.

That being said, some crystal formations are very beautiful and part of nature''s work of art. I know people that love benitoite crystals (they''re very beautiful) and they collect them since they''re often times much more beautiful uncut than cut.

Nature''s beauty:

Ruined by man....

 

[rparker1998]

Date: 1/11/2009 3:57:49 PM
Author: Pandora II

Date: 1/11/2009 1:08:07 PM
Author: rparker1998

DH and I picked this up on vacation but I don''t recall I were, and I think it''s quartz...picture of the host rock to follow in next photo

I have a very similar looking piece that is made up of amethyst crystals.

I wonder if mine isn''t amethyst as well. I was thinknig amethyst or quartz.

 

[T L]

Date: 1/11/2009 4:20:08 PM
Author: rparker1998

Date: 1/11/2009 3:57:49 PM
Author: Pandora II

Date: 1/11/2009 1:08:07 PM
Author: rparker1998

DH and I picked this up on vacation but I don't recall I were, and I think it's quartz...picture of the host rock to follow in next photo

I have a very similar looking piece that is made up of amethyst crystals.

I wonder if mine isn't amethyst as well. I was thinknig amethyst or quartz.

All amethyst is quartz, but not all quartz is amethyst. If it's purple, it's amethyst, if it's not, then it's probably some other kind of quartz.

 

[Harriet]

Date: 1/11/2009 4:20:06 PM
Author: DiaGem
Ruined by man....

Hello! If I find interesting rough, I promise to not ruin it. It would be fun to make up a piece using rough.

 

[rparker1998]

Date: 1/11/2009 4:28:37 PM
Author: tourmaline_lover

Date: 1/11/2009 4:20:08 PM
Author: rparker1998

Date: 1/11/2009 3:57:49 PM
Author: Pandora II

Date: 1/11/2009 1:08:07 PM
Author: rparker1998

DH and I picked this up on vacation but I don''t recall I were, and I think it''s quartz...picture of the host rock to follow in next photo

I have a very similar looking piece that is made up of amethyst crystals.

I wonder if mine isn''t amethyst as well. I was thinknig amethyst or quartz.

All amethyst is quartz, but not all quartz is amethyst. If it''s purple, it''s amethyst, if it''s not, then it''s probably some other kind of quartz.

I guess it''s amethyst then, because as you can see from the pictures previously...it''s purple so thus...based on the above logic. then it''s true...hehe

 

[Harriet]

Date: 1/11/2009 1:47:50 PM
Author: rparker1998
afraid not harriett, all I can tell you is it''s rough but not the ssame texture of gravel, it''s reminiscent of the inside of a malted milk ball for lack of a better description...hehe

I''m checking the Smithsonian''s Rock and Gem guide. It says that "amethyst occurs in alluvial deposits and geodes." The matrix looks like the inside of a geode. Does the other hard layer look like granite to you? If the crystal is rose quartz instead, the matrix is likely to be a pegmatite.

 

[rparker1998]

amythyst rock

That looks just like my specimen. Hubby says we bought it at a cavern/mine place somewhere in OH...a famous tourist place...i''ll have to google it.

 

[rparker1998]

We purchased it at the Seneca Caverns in Ohio. link to seneca caverns

 

[cofor]

I hope I do not seem rude but I can assure you that the matrix is chalcedony/agate (microcrystalline quartz) and the exterior of the piece tells me with 90% certainity it is of Brazilian origin where the geode has weathered out of basalt rock.

 

[Pandora II]

Date: 1/13/2009 6:48:41 AM
Author: cofor
I hope I do not seem rude but I can assure you that the matrix is chalcedony/agate (microcrystalline quartz) and the exterior of the piece tells me with 90% certainity it is of Brazilian origin where the geode has weathered out of basalt rock.

My almost identical looking piece is brazilian - and also bought at a mine (when I was 11 with my pocket money

).

Most mines/mineral museums etc that are open to the public have shops that sell a variety of specimens a lot of which won''t be native to that mine or even that country.

Amethyst is one of the most popular specimens available - it''s pretty durable and affordable.