Aragonite and calcite with pocket of calcite rhombs Chalcedony nodules This flat polished slab of

This flat polished slab of picture sandstone is made from Arizona Sierra sandstone sourced from central Arizona

though it does have some interesting cactus-quartz growth on that top portion

Tiny points of quartz often spot these specimens

Approx size: 2

but overall reaction is poor

Aragonite and calcite with pocket of calcite rhombs Chalcedony nodules This flat polished slab ofLocale: 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