Calcite, San Antonio Mine, Santa Eulalia, Chihuahua, Mexico
This is a large, spectacular, plate of brightly fluorescent, plumose and needle-like calcite scalenohedrons from the San Antonio Mine, East Camp, Santa Eulalia, Aquiles Serdán Municipality, Chihuahua, Mexico. An impressive specimen to view under visible light, this piece really comes to life under short wave UV, showing a bright, saturated, orange fluorescent response. This specimen measures 9.5 x 6 x 2.5 inches and weighs over 2 1/2 pounds.
The San Antonio Mine is located near Chihuahua, Mexico, and is an underground operation that produces sphalerite, galena and cassiterite. The host rock is limestone from the Upper Cretaceous period, dated 100 to 66 million years old.
As shown above, bright, saturated, orange fluorescence is seen under short wave UV (254 nm). This calcite shows similar, but much dimmer fluorescence under mid and long wave UV.
Same specimen, shown under visible light.