I usually do a quick Google search before I post each deskcrop, just to make sure my understanding of the samples I post about isn’t contradicted by other, possibly more knowledgeable folks who have published on the web before me. Normally that means checking the Wikipedia article (if one exists) for the rocks I’m posting about. It’s not uncommon that there are other reputable scientific accounts of the rocks I post about, as well. You can then, perhaps, imagine my disappointment when I got a look at the results of the search term “blue calcite“. I wanted to find a concise scientific explanation for its color causing mechanism, not how it affects my chakra when placed between purple candles. (Though I’m tempted to test whether it can actually “help keep teenagers away from bad influences or company”.)
[Update: A reader e-mailed me to point out this Caltech website that says, "Radiation is associated with blue and amber colors of calcite. Natural radiation interacts with sheared calcite to produce blue colors. An interesting experiment is to break a colorless calcite crystal into chips upto 3 mm in size. When some of the are chips are exposed to ionizing radiation (such as gamma-rays) they turn amber colored. If some more of the same chips are put into hydrolyic press and squeezed (One can use a KBr pellet press such as are used in chemisty laboratories and pressurize the die to the same pressure used to prepare KBr pellets), they will remain colorless. If they are subsequently exposed to ionizing radiation, they will turn blue." Unfortunately, no reference is cited on the website.]
This blue calcite comes from the Valentine Mine, near Harrisville, NY in the Adirondack Mountains. This quarry also happens to be the site of my second cousin’s masters thesis (Hi Martha!). It’s a small world.