The specimen is a dogtooth calcite on sphalerite from the San Antonio el Grande Mine, Chihuahua, Mexico.
The first image was taken under short wave ultraviolet light, which produces a strong red-orange fluorescence from the specimen. The image below was taken under long wave ultraviolet light which brings out a white to yellow fluorescence in the calcite.
To see this specimen under normal lighting conditions, return to the Mexico fluorescent minerals or the Fluorescent minerals section and click on the page link "To view specimen material from Mexico."
Calcite on sphalerite 
Quantity in Basket: None
Code: MCS-100
Price: $60.00
Shipping Weight: 0.59 pounds
Location: San Antonio el Grande Mine, Chihuahua, Mexico.
Minerals: Calcite on sphalerite
Size: 3" x 1-1/2" x 1-3/4"