What is prehnite?

Prehnite is a silicate mineral typically characterized by its pale green to yellow-green color, although it can also be found in colors like white, grey, or colorless. Its chemical formula is ( \text{Ca}_2\text{Al}(\text{Si}3\text{O}{10})(\text{OH})_2 ), indicating it is a calcium aluminum silicate hydroxide. Prehnite often forms in botryoidal, globular, or tabular crystal habits and frequently displays a pearly to vitreous luster.

This mineral is part of the phyllosilicate subclass and can be translucent to semi-transparent. Prehnite is commonly associated with other minerals such as zeolites, datolite, and epidote, and is often found in cavities within volcanic rocks and in some metamorphic rocks.

Regarding its geological occurrence, prehnite is usually formed as a secondary mineral through low-grade metamorphism of mafic igneous rocks. It has been found in locations around the world, including Australia, South Africa (where it was first discovered and described), the United States, and China.

Prehnite is considered a gemstone, valued for its attractive color and unique crystal habits. It is sometimes used in jewelry, although it is not widely known as a mainstream gemstone. In metaphysical contexts, prehnite is thought to promote calmness, peace, and a connection to nature, and is often referred to as a "stone of dreaming" or "stone of prophecy."