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Post by bammer on May 21, 2008 7:29:18 GMT -5
One of the neat things about belonging to a 50 year old lapidary club is the old material that turns up now and then, folks have had it in their storage areas for years and donate it. Last weekends gem show hosted by our lapidary club was well attended. My daughter bid on a bag of rocks in the silent auction and since it was the last auction of the day everything went for 1/2 price. When we were paying the $1.50 for the bag I noticed another bag of similar material and bought that one also. There are some stones I have never seen before. Some look like they would make some nice jewelry. This stone has an interesting stair step formation, and the shape is roughly triangular.  These stones look interesting, some of the green is translucent.   Any thoughts on where they might be from? thanks for any help. |
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Post by lauriesrocks on May 21, 2008 7:33:29 GMT -5
The white piece is difficult to see, especially against a white background, but the bottom piece is definitely opal.
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Post by xtldggr on May 21, 2008 15:38:52 GMT -5
Bammer,
Pretty sure the first picture is calcite, that patterning is very common on slightly weathered pieces. Hardness 3 and reacts with HCL.
The second specimen could be opal, but Chryoprase (green chalcedony) is also a possibility. Opal has a hardness of between 5.5 and 6.5 and Chryoprase is around 7.0. If the specimen can be scratched with a piece of qtz xtl; possibly Opal. If the specimen is not scratched, therefore having a hardness of 7 or greater on Moh's scale, it is quite likely chryoprase. Also, although it dosen't appear like it to me, chrysacolla is a possibility. This can be easily discounted however if the specimen can scratch a penny, as its hardness is around 4.0 and chrysacolla's hardness is somewhat lower at around 2.5.
Happy sleuthing,
John
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Post by arappaho on May 22, 2008 17:16:38 GMT -5
Yeah Bammer,
Can't see the white rock well enough, and even though the cortex
on the pretty blue-green rock looks like opal I was thinking it looked
like some agatized chrysacolla.
Nice find whatever it is.
Joe
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andiroth
Full Member
Must find pretty rocks!!
Posts: 15
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Post by andiroth on May 23, 2008 0:17:53 GMT -5
When I was at my local rock shop today, I saw some stones similar to the bottom photo labeled "gem silica" ... the top photo sure is interesting, does appear to be calcium-type rock. No rock professors in your area? I am quick to pester mine from college!
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pebblepup
Senior Member
Succor Creek Thunder Egg
Posts: 21
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Post by pebblepup on Nov 26, 2008 18:04:16 GMT -5
I am not sure what the blue stuff in the second picture is but I have a small piece that look exactly the same; I tumbled it and it turned out great.
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Post by jpolk123 on Nov 26, 2008 22:15:45 GMT -5
Wow the blue stuff is really purty. It looks like it would cab out good.
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Post by gemlover on Nov 27, 2008 3:10:59 GMT -5
The top one does look like calcite also possibly a mold of a clam that has weathered. Calcite is easy test, drop some vinegar on it and see if it fizzes.
All the suggestions for the second are very good. Just check the hardness.
John
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Post by 4cornersrocks on Nov 27, 2008 13:11:43 GMT -5
I have some gem silica chrysocolla from several locations that resembles the second pic. But, at first glace I thought Blue Peruvian/Andes opal. xtldggr gave you the proper tests so there you go, that way you know for sure. Chrysocolla has a really odd texture when you put your tongue to it, it will stick to your tongue sometimes, but that is not a real test, lol...
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