Prehnite
Videos
Prehnite is an inosilicate of calcium and aluminium with the formula: Ca2Al2 with limited Fe3+ substitutes for aluminium in the structure. Prehnite crystallizes in the orthorhombic crystal system, and
Emerald cut prehnite, 1.85 cm × 1.42 cm, 4.6 grams.
Thin plate of pea-green prehnite on which have grown calcites
Water green color spheres of crystallized prehnite with minor calcite on basalt
Datolite
Videos
Datolite is a calcium boron hydroxide nesosilicate, CaBSiO4. It was first observed by Jens Esmark in 1806, and named by him from δατεῖσθαι, "to divide," and λίθος, "stone," in allusion to the granular
Datolite on sphalerite from San Luis Potosí, Mexico (size: 6.2 x 5.3 x 2.8 cm)
Polished datolite nodule from the Quincy Mine of Michigan’s Copper Country (size: 4.1 x 3.3 x 1.7 cm)