Barium sulfate, when calcined, is “lapis illuminabilis”: the first-discovered phosphorescent substance. #minerals
on 02017-07-13Carved nephrite #minerals are tough enough to make fishhooks and bladed weapons like the mere from. Nephrite, Ca₂(Mg, Fe)₅Si₈O₂₂(OH)₂, is an actinolite amphibole; it contains slightly more silicon than #enstatite, and also contains calcium and hydroxyls, which enstatite doesn’t. How would you go about synthesizing nephrite? Especially without accidentally creating asbestos? #materials
on 02016-12-16Oh my. You can fire #talc to turn it into #enstatite and cristobalite at 1000° to 1200°. Be still, my beating heart! So you could maybe precipitate #waterglass with magnesium to form talc, machine the talc to precise dimensions, and then fire it to dehydrate it and precipitation-harden it into enstatite and silica? And then it’s refractory enough to cast silver in? That’s AMAZING. Can you also reinforce it with some kind of refractory fiber, like basalt fiber (declassified 1995!), as you precipitate it, so that it will have reasonable tensile strength? #minerals
on 02015-08-30"Enstatite", a pyroxene, is yet another magnesium silicate mineral! It’s MgSiO₃, with a 1:1 Mg:Si ratio, in between forsterite’s 2:1 and talc’s 3:4, and it’s not hydrated. It’s around 5-6 Mohs hardness, and forsterite reacts with quartz to form it; apparently it’s possible to hydrate it and turn it into talc. There’s a pyroxene spectrum from enstatite to ferrosilite, FeSiO₃ #materials #minerals
on 02015-08-30No, wait, "forsterite" (an #olivine; Mohs hardness 7! Gemstone peridot!) is magnesium silicate, Mg₂SiO₄. I thought that was talc? Apparently talc is hydrated, so I’m guessing that precipitating #waterglass with magnesium is going to give you something more like talc than like forsterite, which also has a 2:1 Mg:Si ratio, compared to talc’s 3:4 Mg:Si ratio; so baking out the water probably wouldn’t be enough. #Refractory #materials: doesn’t melt until 1900°! (And iron ions, but only iron(II) ions, can replace the magnesium in any concentration.) But wait! There’s #enstatite! #materials #minerals
on 02015-08-30"Olivine" is magnesium iron silicate, which is I guess what you get if you precipitate #waterglass with magnesium and iron salts? Or will the hydration interfere with that and give you a softer and weaker material, like talc? #minerals
on 02015-08-30"Larnite" is calcium silicate, so I guess that’s what you get if you precipitate #waterglass with calcium salts. It’s Mohs hardness 6, a lot harder than talc. Occurring as a phase in concrete, it’s called “belite”. “readily prepared from reactive CaO and SiO₂ at 300 °C.” #minerals
on 02015-08-30Talc is hydrated magnesium silicate, H₂Mg₃(SiO₃)₄, so I guess that’s what you get if you precipitate #waterglass with magnesium salts. (Or not; see below.) #minerals
on 02015-08-30The USGS gives #pricing information on a variety of mineral #materials, including some historical stuff. #minerals
on 02015-08-28