Thomsonite

[Toiv0]

Material I picked up yesterday.

[wigglinrocks]

Wow , some bigguns in the box .

[Jugglerguy]

Those are really nice. The best I've found is U.P. prehnite, and only tiny ones. Are those from Grand Marais, MN?

[toiv0]

I believe this came from when they were updating Hwy 61 by Grand Marais a few years back. Not sure if it came from the last tunnel or the road cut by a turnout. I think I about have a life time supply. probably 100 plus pounds of material in matrix .... now to get it out.

[Fossilman]

Your going to have some nice tumbles.....Thumbs up

[wigglinrocks]

How do you go about getting them out of the matrix ? I think maybe bust away most of the matrix , then be gentle with a chisel .

[toiv0]

Apr 16, 2017 9:36:50 GMT -5 wigglinrocks said:

How do you go about getting them out of the matrix ? I think maybe bust away most of the matrix , then be gentle with a chisel .

Kind of like that. There is a couple of grades of basalt. The darker blue or black is very hard, the brownish colored basalt no much.  So I am doing some experimenting with slabbing the hard basalt and using a core drill to get the stone out and then remove the basalt, haven't tried it yet. Some I cut and use the matrix in the cabachon. The bottom rock in the picture is the brown and you can see the Thomsonite and its round. Those pop right out. The cut stone is bound in pretty tight. I have tried diamond bits to grind around the stone to no avail. 
So I guess its patience patience patience and sometimes a little luck.

[wigglinrocks]

Apr 16, 2017 22:10:04 GMT -5 toiv0 said:

Apr 16, 2017 9:36:50 GMT -5 wigglinrocks said:

How do you go about getting them out of the matrix ? I think maybe bust away most of the matrix , then be gentle with a chisel .

Kind of like that. There is a couple of grades of basalt. The darker blue or black is very hard, the brownish colored basalt no much.  So I am doing some experimenting with slabbing the hard basalt and using a core drill to get the stone out and then remove the basalt, haven't tried it yet. Some I cut and use the matrix in the cabachon. The bottom rock in the picture is the brown and you can see the Thomsonite and its round. Those pop right out. The cut stone is bound in pretty tight. I have tried diamond bits to grind around the stone to no avail. 
So I guess its patience patience patience and sometimes a little luck.

Thanks . Reason I asked , I was pawing around in my rock pile and found a rock we found in the UP by L'Anse I think about 5-6 years ago . Maybe 20" long and has a lot of little nodules on the surface . When we found it , I thought they were tiny little agates . Now I'm thinking they might be Thomsonite . I'll do some more checking on it and see if i can dig a few out without destroying them .

[toiv0]

Apr 16, 2017 22:31:15 GMT -5 wigglinrocks said:

Apr 16, 2017 22:10:04 GMT -5 toiv0 said:

Kind of like that. There is a couple of grades of basalt. The darker blue or black is very hard, the brownish colored basalt no much.  So I am doing some experimenting with slabbing the hard basalt and using a core drill to get the stone out and then remove the basalt, haven't tried it yet. Some I cut and use the matrix in the cabachon. The bottom rock in the picture is the brown and you can see the Thomsonite and its round. Those pop right out. The cut stone is bound in pretty tight. I have tried diamond bits to grind around the stone to no avail. 
So I guess its patience patience patience and sometimes a little luck.

Thanks . Reason I asked , I was pawing around in my rock pile and found a rock we found in the UP by L'Anse I think about 5-6 years ago . Maybe 20" long and has a lot of little nodules on the surface . When we found it , I thought they were tiny little agates . Now I'm thinking they might be Thomsonite . I'll do some more checking on it and see if i can dig a few out without .destroying them .

chances are they might be prehnite which is more common in the UP

[wigglinrocks]

Apr 16, 2017 23:58:49 GMT -5 toiv0 said:

Apr 16, 2017 22:31:15 GMT -5 wigglinrocks said:

Thanks . Reason I asked , I was pawing around in my rock pile and found a rock we found in the UP by L'Anse I think about 5-6 years ago . Maybe 20" long and has a lot of little nodules on the surface . When we found it , I thought they were tiny little agates . Now I'm thinking they might be Thomsonite . I'll do some more checking on it and see if i can dig a few out without .destroying them .

chances are they might be prehnite which is more common in the UP

I'll check for eyes

[toiv0]

Prehnite can be cool, I posted this pic a while ago. Thought it was Thomsonite, consenus is that it isn't. You can see the copper inclusions in the lower left which probably makes it Prehnite. It came out of one of the rocks from the Grand Marais area.

[toiv0]

Here is a some Thomsonite I left in matrix.

[wigglinrocks]

Apr 17, 2017 0:26:15 GMT -5 toiv0 said:

Here is a some Thomsonite I left in matrix.

Pretty stone and nice work . The photos really help to see what I am looking for .

[Jugglerguy]

Apr 17, 2017 0:08:36 GMT -5 wigglinrocks said:

Apr 16, 2017 23:58:49 GMT -5 toiv0 said:

chances are they might be prehnite which is more common in the UP

I'll check for eyes

Prehnite can also have eyes. They're very hard to tell apart, and I wouldn't be very good at it. From looking at examples in the Seaman Mineral Museum at Michigan Tech. in Houghton, it seems that Thomsonite has slightly darker colors and more clear eyes. Prehnite tends to be more blurry and washed out looking.

Here's a good article.

[wigglinrocks]

Apr 17, 2017 9:31:33 GMT -5 Jugglerguy said:

Apr 17, 2017 0:08:36 GMT -5 wigglinrocks said:

I'll check for eyes

Prehnite can also have eyes. They're very hard to tell apart, and I wouldn't be very good at it. From looking at examples in the Seaman Mineral Museum at Michigan Tech. in Houghton, it seems that Thomsonite has slightly darker colors and more clear eyes. Prehnite tends to be more blurry and washed out looking.

Here's a good article.

Thanks Rob , good read in the article . I will do some looking at my rock and see if I can distinguish the difference . Or just call them either - or .