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Geologic glasses are all vaguely unnerving in how they form, but trinitite amps up the discomfort to "Let's just not."
Q: What's a geologic glass? And why are they inherently unnerving?
A: A geologic glass is something that lacks regular crystalline structure, which means it was super-hot then cooled so fast it didn't have time to get organized.
If you find glass, you know shit went down.
A: A geologic glass is something that lacks regular crystalline structure, which means it was super-hot then cooled so fast it didn't have time to get organized.
If you find glass, you know shit went down.
Obsidian: Lava that cooled ridiculously fast. Most commonly-known geologic glass. Sharp. A wee bit harder than window glass.
Dense microscopic embryonic crystals (wee babies) make it opaque -- spherulites might give it swirly bits, microlites can make it polarized.
Dense microscopic embryonic crystals (wee babies) make it opaque -- spherulites might give it swirly bits, microlites can make it polarized.
Tektite: Shards melted by impacts (think the splash of a meteorite smashing into the ground). Chemical composition is literally anything because it's whatever the rock was that got smashed.
Frictionite: My horrifying fav -- rock melted by a landslide so freaking big the friction melts the ground. Think how devastatingly big that landslide is...
I love mine with all my heart & regularly bring it out at parties to make other people admire it.
I love mine with all my heart & regularly bring it out at parties to make other people admire it.
Fulgurites: Rock melted by lightning strikes.
Some artists create this artificially by jabbing lightning rods into sand.
Lechatelierite is kinda up for debate, but is probably sand melted by lightning but maybe by impactors. It's a bit TBD & I don't like it as jargon.
Some artists create this artificially by jabbing lightning rods into sand.
Lechatelierite is kinda up for debate, but is probably sand melted by lightning but maybe by impactors. It's a bit TBD & I don't like it as jargon.
Maskelynite: melted by shockwaves. Probably abrupt quenching from a high-pressure shockwave, but debatably from low-temperature low-pressure shockwaves. As far as we know, always from impactors, but in theory could show up from human-generated explosions.
Not all glasses are shiny -- pumice is a vesicular glass (ie, full of holes from bubbles), so gassy lava that cooled abruptly.
...which means the pumice you use to scrub away callouses is close kin to obsidian. Surprise!
...which means the pumice you use to scrub away callouses is close kin to obsidian. Surprise!
And not all glasses have pretty names -- combustion-metamorphic glasses are relatively common when coal seams burn underground, continuing the theme of "Oh, now that's a bad day" but without tidy jargon.
Meanwhile, humans create all kinds of glasses -- common glass, lead glass, crystal glass, & all sorts of melting oddball things into glass (Mt St Helens Stone, andara garbage dump glass...)
Sometimes people think opal is a glass, which breaks my "how this forms unnerves me...". But! Opal isn't a true glass OR a true mineral! Its internal structure makes it a mineraloid.
Opal is pretty because of its lattice of spheres, but it doesn't have a set repeating pattern.
Opal is pretty because of its lattice of spheres, but it doesn't have a set repeating pattern.
Yup. Corium is glass from a meltdown, effectively lava made from nuclear reactor fuel.
Yup! All glasses break with a characteristic conchoidal fracture (& razor-sharp edge) that is a direct result of its lack of crystal structure. And like more common domestic glass, they can all produce sharp shards so handle with care!
Impact events are dramatic enough they create several types of glass, not just the splatter-tektites. (They're an entire chapter in Traces of Catastrophe: lpi.usra.edu/publications/b…)
My fav? fladen, aerodynamic glass bombs.
My fav? fladen, aerodynamic glass bombs.
Q: So... could I make a lens out of geologic glass? A mirror? A window? A pointy fren?
A: It's not necessarily a good idea, but technically? Yeah, you probably could depending how big it is.
A: It's not necessarily a good idea, but technically? Yeah, you probably could depending how big it is.
