We just visited my folks in NC, and took the kids to one of those “Gem Mines” in the area. Basically they give you a bucket full of rocks and you pan though the pebbles and dirt for ‘gems’. They have examples around so you know what to look for. We found out that one of the stones we had saved from the bucket was an aquamarine, and that to change the color from almost clear to blue, they heat it. I didn’t want to do any messing around on my mom’s electric stove, so I wondered, what if I put it in the microwave? Would the stone change color? Would the microwave be damaged? Would it explode from being saturated? How long should I leave it in if I decide its safe to do it?
Aquamarine is a form of beryl, a ceramic (Be[sub]3[/sub]Al[sub]2[/sub]Si[sub]6[/sub]O[sub]18[/sub]) of beryllium metal. Like most ceramics, it’s not very electrically conductive, and so won’t have large currents induced in it by microwaves, and most likely won’t get any hotter than any other ceramic, such as a coffee cup, would. My educated guess is that it would do nothing of interest. If you do decide to try, put a glass of water in the oven cavity along with the stone to absorb the microwave energy so it doesn’t all get reflected back to the magnetron.
Would it be a good idea to put the stone in the glass of water?
I can’t tell you how to do it, or if its safe in a home microwave, but my brother once work for a company that installed large xray and microwave equipment, mostly for the government.
Except, once where they installed microwave equipment for doing just what you’re talking about. The client was mass producing Blue Topaz. They did several other semi-precious novelty gems too.
I know the stuff he installed was huge, high powered, killyoudeadrightnow stuff. Whether that was to do large quantities, or because they needed very high temps, I can’t say.
I can’t remember if aquamarine is a form of Quartz or not, if so I think the recrystallization temp is around 1400˚-1500˚ F
Along the same lines as Loopydude, I was thinking you should try dropping the stone into a cup of boiling water. Can’t hurt, can it? And that way you don’t destroy the stove or the microwave.
Boiling water wouldn’t be hot enough.
To get those temperaures, you’ll need a high-temperature oven; in my lab, I’d use the muffle furnace. A blow torch might do the job.
Wow. 400-450 deg. C is pretty hot. That’s well over the melting point of lead and tin. Can a typical home microwave or oven even heat something to those temperatures?
450[sup]o[/sup]C is around 850[sup]o[/sup]F, which is well within the temperature range of a self-cleaning oven (900-1000[sup]o[/sup]F).
A conventional oven, no–not even on self-clean mode. A microwave oven can, under some conditions, produce localized heating to much greater temps. You can make free-floating plasma balls that can exceed 450 C easily (I heartily don’t recommend it, though). Nevertheless, for the purpose the OP has in mind, I’d have to say a microwave oven is unsuitable.
I did’t think they got that hot. Wow.
Mmmm. Plasma balls…
I put what I thought was an aquamarine stone into the microwave with a glass of water, I figured what the heck, the microwave is on its way out anyway. Two minutes. Nothing happened. Didn’t even get warm. Disappointing right? I then put it on a slotted spoon over the flames of the range, never changed color, and eventually it cracked and went sailing in pieces all over the room. :smack: I’m guessing it was probably a piece of quartz. Also I would tell you its a bad idea to dump the hot rock into a pan of water after you’re done heating it.
Off I went to get other rocks that were more likely aquamarine. And some safety glasses. I found some clear pebbles with just a blue tinge to them and put them in the spoon over the fire. They changed color after a minute or so, but not to anything vibrant, they’re closer to light blue now. I would heat them longer but the way that other rock zinged across the room really surprised me. Next time I’ll try to put them in a pan in the barbecue for a longer amount of time.