24 Mar '17, 9pm

#FluoriteFriday! #GEOL108_GEOL121

150 to 200 million years ago, hot water containing fluorine and other minerals was forced up from deep within the Earth. When this brine reached the calcium rich, limestone bedrock, fluorite crystals formed along the walls of fractures and voids in the rock. Flat layers of fluorite also formed parallel to the limestone beds, replacing the host rock.

Full article: http://www.museum.state.il.us/gallery2/main.php?g2_itemId...