Aragonite and calcite with pocket of calcite rhombs Chalcedony nodules Approx size: 2

Approx size: 2

This calcite specimen from Santa Eulalia has a layer of calcite druzy with several larger modified rhombohedral calcite crystals perched atop

creating a bold line that touches the surface on one side

The starbursts in the rhyolite are spherulites: minerals composed of dense radial needle-like growth from a point to create a sphere (hence "spher"ulite)

Aragonite and calcite with pocket of calcite rhombs Chalcedony nodules Approx size: 2Locale: Sidi Ayed, Fs Mekns Region, Morocco Approx dimensions: 3. 5 x 2 x 2" Approx size: 425g (0. 9 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