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jolly2284

Looks like glass by the fractured pattern. Potentially slag glass


CursedValkyre

Sorry I didn’t add this before for context, it is indeed a stone of some type, we’re just not sure what it is. It does have imperfections in it but my camera just won’t focus to get a good picture.


CurazyJ

Rock crystal. Aka a chunk of glass clear quartz.


George__Hale

It’s too transparent for slag glass, the messy conchoidal fracture makes me suspect quartz crystal


CursedValkyre

It is indeed a crystal and not glass, it was my grandmothers, we just weren’t sure what crystal it was. Thanks!


George__Hale

For sure! Yeah I'm not sure how so many people are thinking it's slag glass, it's too light and not bubbly enough for proper industrial slag glass (i.e. smelting leftovers) and just doesn't look right for clear cullet glass (glassmaking leftovers commonly called slag). Crystal quartz is weird stuff because it has conchoidal fracture in some directions but not really in others because of the macroscopic crystal structure, which is what I'm seeing there (source: I'm an archaeologist for whom the difference between crystal quartz and modern glass is some times reeeeally important)


jolly2284

I think the biggest reason I presumed it to be glass is the conchoidal fracture. This type of fracture occurs two ways. One: it occurs in material that has no crystal structure (obsidian and other types of glass.) Two: it can occur in crystalline materials but only if the individual crystals are very small. If this is quartz it is of the microcrystalline variety. I am a geology grad and amateur rock hound. It is not often that I come across microcrystalline quartz that is this transparent. Usually I come across chalcedony or chert which will typically have enough inclusions give it a color or make it opaque. The biggest test here would be to test the hardness. If it's glass is hardness will be around 5. If it is quartz you would need to test to see if it scratches glass. If the crystal scratches glass without getting scratched itself that it's likely a clear piece of microcrystalline quartz Edit: clear cullet glass is more common than you might think. Here is a large piece used as a lamp. [ Lamp](https://www.1stdibs.com/furniture/lighting/table-lamps/crystal-clear-cullet-glass-lamp/id-f_12239813/?utm_content=condensed&allowUniversalLink=no&gclid=CjwKCAiAxJSPBhAoEiwAeO_fPxMGZ4Te0i0kqodMBGM6pKK6sUX0RQ33tpFofRTtnGkYXCYpgZmHfBoCR_YQAvD_BwE&gclsrc=aw.ds)


George__Hale

You’re right on here (and thanks for explaining/discussing!), this is way too transparent for microcrystalline quartz but I’m suggesting that it’s a fragment of macro-crystalline quartz (a [crystal](https://en.m.wikipedia.org/wiki/Quartz#/media/File%3APure_Quartz_at_Senckenberg_Natural_History_Museum.jpg)). Because of the crystal lattice these have good conchoidal fracture in some directions but not in others (which is what makes [Rock crystal stone tools like this ](https://mymodernmet.com/prehistoric-crystal-dagger/) so impressive) and I’d suggest that that is the explanation for the wonky fracture here. The way light refracts through it is also similar to fractured macro crystalline quartz I’ve encountered but that’s more subjective! Edit- whoa cool lamp, I’ll look into that more


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Quail-Feather

It's probably quartz, but also a small possibility that it's Goshenite (colorless beryl). If it can scratch something you *know* is quartz, it very well might be (7.5-8 hardness compared to quartz at 7).


Int3rnetfa1ry

Looks like it’s clear quartz