Calcite in a Bucket

The last week or so has been dedicated to seeing if I'll break some calcite if I cool it to liquid nitrogen temperatures (77K). I dunked a chunk a while ago and it fractured. As expected. Now I've built a low-tech "dewar" to try to slow the cooling rate down. This time it didn't break much, but it only came down to 100K or so in about 20 minutes. Oh well. Time to build a better dewar since styrofoam and cardboard didn't work. At least my temperature-sensor (diode) does.