CCCXC
Argilla electrica
Pointed Schorle
When I was at the Logan Rock, well known in Cornwall, I gathered this specimen within a few yards of it out of a very large solid massy vein of Quartz. It ran some length into the Quartz, but owing to my want of time and tools I could not ascertain how far. This specimen is of a close hard texture, and finely polished, which approaches what may by some be called the Tourmaline variety; it has a slight greenish hue when viewed so as to transmit the light, and is more or less covered with the prismatic iridescence.