In the process of going through things at mom’s, I spent some time looking through a bunch of rock. I’m not sure what it is about rocks and our family, but it seems we all have a rock collection of some description. Mom also had some rocks and minerals that had been her fathers, including this large calcite crystal. A large section of the crystal is opaque but the left side as shown here is mostly transparent. Calcite crystals have an interesting optical property called birefringence, that is, they have a double refraction, causing two images of any items viewed through the crystal. As you can see here, the word Library (on a Modern Library copy of The Aeneid) is duplicated when viewed through the crystal.