Tenebrescence...

[jonsinger]

...is a form of photochromism that occurs in a few minerals; the ones I’m aware of are forms of Sodalite. The piece I show here is Hackmanite, which is probably the best known, and was the first type I learned about

Comments

[xiphias]

So. Freakin. COOL!

[jonsinger]

'Tis that. When I first read about Hackmanite I don't recall any photos, so I had to imagine what it was like. Much more recently I went looking for it on eBay, and that's where I got the samples I currently have. It was only last weekend that I tried putting the little blacklight right on top of one of them (which results in better color change than other methods I've used), and then the white LED bleaching notion.

Anyway, glad you like it.

[alecaustin]

That's awesome. Thanks for sharing these photos and your description of the process with us.

[jonsinger]

My pleasure; glad you like the posting.

I would be really pleased if I could get a glaze to do something like this. There are a few photochromic glazes, but the color change is fleeting, and nothing like as pronounced as what you get with the Sodalite minerals. I've also had one report of a thermochromic glaze that changes color at temperatures that are reasonable, but haven't seen any confirmation. I do get modest thermochromic effects in a few of my own glazes/materials, but only at well over 100 Celsius, which is rather annoying. (When I make ruby dust [this turns out to be trivially easy] it is mauve to lavender as it comes out of the kiln at about 200 or 250 C, and changes to the expectable pale magenta as it cools.)

Hope to see you in June.

[alecaustin]

Heh, yeah, thermochromic effects that only trigger well over 100 Celsius aren't really practical to show off outside of a kiln.

I hope to see you in June as well!

[randomdreams]

That is amazing. I'd never heard of that.

[jonsinger]

It really is quite something, and not all that common. I have other fluorescent Sodalite samples, some of which are even from a locality where Hackmanite occurs (and fluoresce about the same orange under LW UV), but do not change color. Go figure.

[jonsinger]

Hey. My pleasure; very glad you liked it!

[perspicuity]

that's pretty cool

#

[jonsinger]

Not only is it spiffy, it's relatively cheap; I think I paid 6 or 8 bucks for that chunk. Some of them do go higher, though, and a really good piece of Tugtupite is unaffordium as far as I'm concerned.