Not very interesting, just ceramic grade barium carbonate. My source of barium. Not real pure, it farts when you dissolve it in HCl -- it gives off H2S, hinting at its manufacture. You see, barium sulfate (barite) is pretty much the most common barium mineral, but it's damn hard to do anything with. You can't simply boil with sodium carbonate to remove that sulfate ion. What they do is grind it up and roast it with charcoal out to about yellow heat, which reacts BaSO4 + 4C = BaS + 4CO. The barium sulfide is hydrolyzed, giving off H2S gas (which is probably dealt with as other industries do, by partially burning it, producing steam and nonpoisonous sulfur) and leaving barium in some form or another, which is reacted with a carbonate or CO2, finally leaving BaCO3 of some purity. Some BaS hitches a ride, making a smelly experience later (that BaS-tard).
My baggie of barium chloride dihydrate, BaCl2·2H2O. This was produced by dissolving carbonate in HCl and evaporating the solution, producing crystals an awful lot like clear mica plates...except water soluble. The tint of green is from iron, which shows up even though the acid is more or less clear and the barium carbonate is white. Despite washing this stuff twice, the green refuses to dissolve, so, what the hell..
And uh...barium isn't real healthy. According to a typical MSDS, the rat LD50 (the dose where half of the rats tested eventually die) is about 120mg/kg, or about 10 grams for an adult human (if humans and rats scale like that; the dose may be much lower). This baggie contains enough to poison probably 10 or 20 persons, then. Heavy metal poisoning isn't great, hence the crummily drawn skull and crossbones.
Here's a recent sample of some new product. Unfortunately the mica shaped habit didn't photograph well, but I can assure you it is there. Being from the beginning of a new batch, these crystals are very pure, clear and white, hardly any detectable hue of iron impurity. The remaining solution has a slight color to it, which will likely get stronger as the BaCl2 continues to crystallize out. At that point, I'll just toss in the earlier green stuff and recrystallize a few times. See if I can get it all white...
Solubility aside, BaCl2 is pretty stable stuff. Chlorides above it, like MgCl2 and BeCl2, tend to hydrolyze, but BaCl2.2H2O dehydrates uneventfully, fusing to a clear, mobile liquid at red-orange heat as most chlorides do. (Oddly, the melting point is listed as orange to yellow heat (~900°C), and I'm sure my visual thermometer isn't that bad. This stuff may be less pure than I think, or else I've been away from fire for much too long.)
This stuff is one of my more useless chemicals. It's essentially inert, because there's nothing you can do to upset the ionic pair -- you can't boil with soda, because Ba(OH)2 is soluble, and BaCO3 is insoluble but in fact more soluble than SO4. Acids don't do jack because sulfate is a strong mineral acid with a relatively high boiling point, and a stable ion at that (I bet even hydrofluoric acid isn't going to do anything, though fluorine gas probably displaces the oxygen, giving off SF6 and leaving BaF2). It can, of course, be reduced, and carbon is a cheap way of doing that. Another good reducing agent is magnesium or aluminum (or my preference, a 50% alloy of both, magnalium), both which react, shall we say energetically, with the sulfate ion. Possibly with a chlorine donor, this should produce a green flame, flash or strobe (depending on how it burns), as is the spectral behavior of barium.
As chemically useless as barium sulfate is, it does have uses. It is one of the few heavy metal compounds that is insoluble and indigestible by the human body. As such, it is used in medicine to give contrast on x-ray images. Yes indeedy, that icky "barium milkshake" is made possible thanks to your good friend sulfate!
This is my current store of nitrate ions, produced from some spare fertilizer listed as containing ammonium nitrate. I dissolved the fertilizer, added barium chloride solution and evaporated it down, removing the white barium nitrate crystals, which have low solubility (on par with potassium chlorate). The product is brown due to rust on my grinding surface. This salt, when mixed stoichiometrically with magnalium powder, burns in starts, producing a very bright, greenish strobe (that isn't too easy to ignite).