[Rockhounds] What the heck is this

[Rock Currier]

I got an ebay parcel recently, and there was something in it that  has
me stumped...my first thought was some sort of green turquoise or odd
colored variscite or even an off colored chrysoprase as it was a dark
green material that formed  in a seam with a crusting on the
outside....like you see sometimes with turquoise, gem silica,
chrysoprase etc.....so, I split it down the middle and cut a pair of
matching stones but 1 still am not sure what they are.

Dear Jeanne,

Your polished piece of rock is typical of the countless bits of various 
kinds of rocks that are fashioned each year by the lapidaries around the 
world. The Chinese lapidary factories are currently churning the stuff out 
by the ton though most of what they make is a bit more attractive. Typically 
some interesting looking rock type, usually rich in one or more minerals 
comes to the attention of the factory or a home lapidary and it is turned 
into to some cut and polished object. The cutter certainly doesn't know what 
the stone is in any scientific way and frequently doesn't know where the 
rough is from, like your example. In China there is little hardly ever any 
attempt to characterize the rock type in any scientific way, only to try and 
capitalize on it commercially. I use China as an example because that is 
where most of the large lapidary factories are located; some of them have 
more than 500 people working six days a week to churn the stuff out.



We of course see exactly the same kind of activity taking place today in the 
rest of the world. Rarely is any serious attempt made by the lapidaries to 
determine what it is they are working with. Instead they are more anxious to 
give it a name that will make it possible to sell the item to others with 
maximum profit. To do this, a name is frequently invented that will 
facilitate the sale of the material often trading on a name with higher 
value like smoky topaz=quartz or Herkimer diamond=quartz, etc.



In northern China, there is a deposit of pretty translucent green stone that 
has been mined for generations and can be found fashioned into carving and 
jewelry and is seen in most jewelry stores in China and many others 
throughout the world. When you ask the Chinese merchants who sell the item 
what the stone is, they tell you it is jade. If you point out to them that 
it is way to soft for jade, they alter their story a bit and say it is "new 
jade". X-ray analysis of one piece of this material that I had made at the 
Hunan Geological Survey in Changsha, Chins, showed that it is mostly 
antigorite, one of the minerals in the Kaolin-Serpentinite group. However if 
you tell people that, it is quickly apparent that most of them don't want to 
know that and it goes in one ear and out the other. They prefer the name new 
jade. There are other items like Dalmatian stone and spinach stone, among 
many others, that I have not bothered to characterize, which are sold in 
large quantities. Those names seem to serve well, most people really don't 
want to know more than that and if they do they are not willing to go to the 
effort or expense of further investigation. About the most they are willing 
to do is to do as you have done, namely show it to other people in hope that 
someone will give them more information. Are you looking for some sort of 
common name for the stone you cut or are you interested in characterizing 
the stone in a scientific sense?



You can, of course, approach one of the few remaining mineralogists and see 
if you can interest them in working on your stone. It has been my experience 
that these scarce individuals are already loaded with requests for free 
analysis and that they will usually not consider working on a mineral/rock 
unless at least the locality is known with certainty, and I don't mean just 
a country name. In addition it must usually be of further interest to the 
mineralogist because it relates to their particular specialty or a problem 
they are working on. To characterize your particular rock would not be an 
easy task. Perhaps a thin section of it might have to be made and examined 
with a petrographic microscope. This would give insight on how many 
different minerals would be in the rock. Beyond that you could have a 
microprobe made of the various mineral grains to give an elemental analysis 
of many of the mineral grains. With this data, perhaps a name(s) could be 
given to your rock.



I would think that from looking at the pictures of the stone you asked about 
that the material is not distinctive or attractive enough to have even been 
given a common name. If this is so, you make up any name you desire and it 
would serve as well as any other. Good luck with your quest. I hope someone 
more knowledgeable than myself will be able to help you further.

Rock