Prehnite

Hardness: 7 on the Mohs scale. Color: Pale green to light green, often with a translucent to opaque appearance. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (trigonal) crystal system. Cleavage: None. Specific Gravity: Approximately 2.65.

Prehnite typically forms as a secondary mineral in the veins and cavities of mafic igneous rocks such as basalt, diabase, and gabbro. It forms at relatively low temperatures and pressures during the alteration of these rocks, often associated with hydrothermal activity. Geological Age: Varies depending on the host rock, but commonly found in rocks from the Mesozoic to Cenozoic eras.

Primarily used as a gemstone in jewelry due to its attractive color and translucency. It is often cut into cabochons or beads, as seen in the image. It is also collected by mineral enthusiasts.

Prehnite is known for its distinctive botryoidal (grape-like) habit but can also form tabular or prismatic crystals. It is sometimes found alongside zeolites in volcanic rocks. In some spiritual practices, prehnite is considered a stone of unconditional love and a calming influence.

Identification in the field: Prehnite can be identified by its characteristic pale green color, often waxy luster, and its common occurrence in botryoidal or globular aggregates. It scratches steel but not quartz. Common locations: Notable deposits include the Karoo Basin in South Africa, Australia (especially New South Wales), China, India, Mali, and the USA (New Jersey). Tips for collectors: Look for it in amygdaloidal basalts and other altered igneous rocks. Its botryoidal habit is a key identifying feature.