Translucent stone

SueBee · Post by **SueBee** » February 6th, 2018, 8:34 am

Found this stone in my collection but as it is many years (could be 40!)since I collected it I cannot remember where or when I got it or even exactly what it is ( these old brains are a sieve these days

). It is translucent green with white fossil inclusions and I am thinking it will make a nice Suiseki if I can clean it up a bit more. Any ideas how to get the scale off it anyone? Am now wishing I was still a member of the Gem Club.

2012-06-03 20.05.29.jpg

2012-06-03 20.05.44.jpg

bodhidharma · Post by **bodhidharma** » February 6th, 2018, 10:21 am

A wire brush attached to a dremel works well.

Beano · Post by **Beano** » February 7th, 2018, 9:33 am

Does it scratch easily? Looks a little like soap stone

SueBee · Post by **SueBee** » February 7th, 2018, 1:45 pm

Thanks Beano, you reminded me I still have my little stone carving station out in the shed and dremel in the studio...will get them out and have a go. From what I remember of trying before I think it may need acid rather than sweat to clean it.
Bhodi it is as hard as quartz really, hardly can cut it at all. Not soapstone have some of that too but totally different to this. I did try carving a piece years ago and it was too hard/slow. I wondered if the inclusions were what the Japanese/Chinese?? call Chrysanthemum stones?

Beano · Post by **Beano** » February 7th, 2018, 3:53 pm

Ha, definitely not soap stone then, that stuff is soft as.

shibui · Post by **shibui** » February 7th, 2018, 6:09 pm

Quartz is probably the most common clear/ translucent stone but there will never be fossils in quartz. There can be other inclusions that can add interest and I suspect that's what you have here.
Acid should will clean most of the dirt off the stone but give it a test with a small drop first. If it is some form of limestone the acid wash might dissolve the entire stone.
A tooth brush and soapy water is another alternative to try

SueBee · Post by **SueBee** » February 8th, 2018, 8:25 am

OK folks back to the drawing board...the dremel didn't touch it even with a diamond burr it barely made a mark and wore out the diamond fast. I will get some Muriatic acid today and try it...definitely in the quartz hardness range I think. Maybe Jadeite????? ...but that is usually softer I think?

JPG · Post by **JPG** » February 8th, 2018, 9:50 am

It's a form of silica known as chalcedony from I can see....those white bits are where it has been effected by water over time (geological time). Chalcedony is a hydrated form of silica (ie it's quartz with a bit of water). Not surprised the dremel didn't touch it as chalcedony is very fine and extremely hard. If you break it with a hammer, you'll find it breaks like glass with concave fractures and very sharp edges...it's essentially flint.

SueBee · Post by **SueBee** » February 8th, 2018, 12:27 pm

Thanks for that info JPG, if the acid doesn't clean it I will take it to the gem club and ask for advice at the back-to next month.

JPG · Post by **JPG** » February 8th, 2018, 2:41 pm

As a quick test, if you put a drop of dilute acid (assuming hydrochloric HCl) on it it should not do anything. If it's calcium carbonate (limestone, don't think it is) the acid will fizz. It's how we geos test for carbonates in rock.

george reissis · Post by **george reissis** » August 14th, 2018, 12:55 am

Whot you have there is prehnite crystal

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