Glassy Light Green Material???

[Birdy45]

who can help me with this material type? when i was in early elementary a older kid whos grandfather owned a rock shop and was a major collector smashed his grandpas rock in the play ground. my friends and i recovered the left over chunks and ive held on to it ever since. in my oppinion, one of the most beautiful rocks ive seen. thanks for any help on this one -cole

[greywolf22]

Might be slag glass. Pretty material.
Jack

[Birdy45]

thanks jack. so its not natural is it? how would one tell if it is glass or rock?

[greywolf22]

It looks consistant in color, that is why I say slag glass. It looks like the color of some glassware I have seen.

[Birdy45]

alright slag glass it is thanks jack. theres a lot i need to learn as you all can tell lol.

[Birdy45]

you think i should try a hardness test on it to make sure? or is slag glass the only thing you have seen like this?

[greywolf22]

Sure you can. I have not seen any material made by mother nature that looked like that, but there is a lot I have not seen.
Jack

[painshill]

Hi Cole
I'm inclined to agree with Jack... it's very glass-like with highly conchoidal fracture. If it is a mineral, then the only likely candidate would be chalcedony and a hardness test will readily establish that.
Ordinary window glass (and steel pen-knife blades) have a hardness of about 5.5 whereas chalcedony has a hardness of about 7 and so will easily scratch both of those. A good steel file has a hardness of about 6.5 and will just be scratched. Make sure you wipe the scratched surface with a damp cloth after you do the test to be sure you have actually made a scratch rather than just left a residue.
If it is chalcedony, it's a particularly nice gem quality piece.
Roger

[turkeytail]

Looks like vaseline glass...just for sh#ts and giggles put it under a black light if you have one. Vaseline and custard glass have uranium salts and uranium oxide in them and glow under a black light.

[Birdy45]

how hard should i press? i tried it pretty hard with a file and no scatch line was visable. then i tried really hard and got a scratch. so it must be slag or vasaline glass. strange that a rock shop owner owned it. and ill try my dads blacklight tomorrow hes a vet and uses it to look at ringworm lol.

[painshill]

Birdy45 wrote:

how hard should i press? i tried it pretty hard with a file and no scatch line was visable. then i tried really hard and got a scratch. so it must be slag or vasaline glass. strange that a rock shop owner owned it. and ill try my dads blacklight tomorrow hes a vet and uses it to look at ringworm lol.

  For a hardness test you should be applying firm pressure. Imagine you're scoring a ceramic tile or a piece of window glass with a cutter before snapping it to shape.
If sounds like you may be bordering on a hardness around 6.5 - 7 which would be out of range for normal glass but within range for chalcedony. Interesting to see if if has any ringworm. :laugh:  Keep us posted.
Roger

[greywolf22]

This may be Chrysoprase a gemstone variety of chalcedony, a cryptocrystalline form of silica, that contains small quantities of nickel. Its color is normally apple-green, but varies to deep green. If it is its like Roger says if it is Chalcedony its in a very pure form. 
Here are two examples;


  Jack

[Birdy45]

tried the blacklight. no glow. so im leaning tward the chalcedony. also when i hold it up to the light it has lighter, more clear streaks and swirls. if a gemstone quality piece is it worth anything? not selling it just would be cool to know.
-thanks cole

[greywolf22]

Cole
Do not know the value.
Jack

[painshill]

Birdy45 wrote:

tried the blacklight. no glow. so im leaning tward the chalcedony. also when i hold it up to the light it has lighter, more clear streaks and swirls. if a gemstone quality piece is it worth anything? not selling it just would be cool to know.
-thanks cole

  Cole
As gemstones go, it's "semi-precious" (although nice). You could probably pick up a piece like that at a rock -and- gem show for somewhere between 15-20 bucks depending on how good you are at haggling. Converted to a nice large cabochon it might fetch 40-50 bucks. The large chunk you said it came off would be a different story. Worth rummaging around for if it still exists.
Roger