what is this?? rock?? glass??

[gods country girl]

i have this posted in the what is it forum.i found it in a pile of rocks.I was thinking it was a chunk of glass, but it is very heavy.anyone have any ideas on what it could be??

[lamar]

Dear god's country girl;
It could be a form of chalcedony known as agate. Go here to read my thread about inexpensive jewelry/gold/stone identification kits.
http://forum.treasurenet.com/index.p...07786.html#new
Your friend;
LAMAR

[Eu_citzen]

Flourite?

[emtrescue]

I'm no expert by any means, but I'm going to take a stab at this one. I'm going to assume that you found this in PA. (went through some posts to come to this conclusion)

Anywhooo -

I think this is serpentine, well a polymorph of serpentine called Antigorite.


Just a guess, but here's a copy and paste of the Antigorite section:

Lamellated antigorite occurs in tough, pleated masses. It is usually dark green in colour, but may also be yellowish, gray, brown or black. It has a hardness of 3.5–4 and its lustre is greasy. The monoclinic crystals show micaceous cleavage and fuse with difficulty. Antigorite is named after its type locality, the Valle di Antigorio in Italy.

Two translucent varieties of antigorite, bowenite and williamsite, are prized by artisans and collectors for their ornamental value; these are the “precious serpentines”.

Bowenite is an especially hard serpentine (5.5) of a light to dark apple green colour, often mottled with cloudy white patches and darker veining. It is the serpentine most frequently encountered in carving and jewellery. The name retinalite is sometimes applied to yellow bowenite. The New Zealand material is called tangawaite.

Although not an official species, bowenite is the state mineral of Rhode Island: this is also the variety’s type locality. A bowenite cabochon featured as part of the “Our Mineral Heritage Brooch”, was presented to First Lady Mrs. Lady Bird Johnson in 1967.

Williamsite is oil-green with black crystals of chromite or magnetite often included. Somewhat resembling fine jade, williamsite is cut into cabochons and beads. It is found mainly in Maryland and Pennsylvania, USA.


From this link: http://rockhoundblog.com/regular-pos...ock/#more-1013

Just a S.W.A.G. though....

[Eu_citzen]

I suppose you forgot about the high density?
Flourite has a SG of around 3.0 to 3.1 or so.

Also the colour variation would signal Flourite.
Serpentine does usually not vary as much in one single small specimen.
It usually keeps to one or two colours.

Flourite is also much more common as a hydrothermal mineral.
If this pile of rocks would be a mine dump.. It would be even more logic.

Also notice this piece is massive.

[emtrescue]

You're probably right actually. On my laptop it looks completely different than on my desktop (and mobile for that matter.) It looked dull on my laptop and it reminded me a little of jade so I had it in my head serpentine.

Anyways - wonder what this looks like under a UV light?

[AMorgan]

Many guesses ignored the obvious... Conchoidal fracture eliminated 95% of the possibilities. Glass slag is the most likely answer as those color combinations along with the "glassy" surface seldom occur together naturally.

[Tuberale]

Maybe colored glass slag, or even colored obsidian, which can come in many colors. I really like the greens in this stone.

Atypical in my experience for serpentine, which chemically is the same thing as asbestos and jade, btw. I have a chunk of polished black jade near me, and this looks too transluscent for that.

Another possibility, though: opal, which also fractures like glass, but is quite brittle.

A streak test will prove or disprove many of these possibilities.

[Joe Hoo?]

it's not glass thats for sure but its pretty could be several things HH