Aragonite and calcite with botryoidal side Geode There are some very small

There are some very small calcite crystals sprinkled on the piece

Daylight fluorescence means the material reacts to the UV in sunlight

This piece is covered with around two dozen hydroxyapophyllite crystals

Portions that fluoresce red also have very brief phosphorescence

I have most frequently seen this Madagascar material attributed to prehistoric turtles that once roamed the area

Aragonite and calcite with botryoidal side Geode There are some very smallLocale: Sidi Ayed, Fs Mekns Region, Morocco Approx dimensions: 3 x 2. 75 x 2" Approx size: 480g (1 lb) Calcite and aragonite are polymorphs of one another, meaning that the same chemical composition (calcium carbonate) has crystallized into different crystal structures (trigonal and orthorhombic, respectively). Calcite and aragonite often grow together, and the two minerals are also frequent paramorphs of one anothera pseudomorph of the same chemical