What is Mesolite?
Mesolite is a classic cavity mineral: a dark basalt matrix can carry a cloud of bright white needles that looks almost textile. The spray records slow zeolite growth from fluid moving through once-hot lava.
Mineralogy and crystal structure
Reference formula: Na2Ca2Al6Si9O30·8H2O. Mesolite is an orthorhombic zeolite in the natrolite-scolecite series. Its fine needles commonly form sprays with natrolite and scolecite, making the association more reliable than colour alone. Mesolite is classified with silicates and has a orthorhombic crystal system. Typical hardness is 5–5.5 on the Mohs scale and specific gravity is approximately 2.2–2.3.
Colour, lustre and habit
Typical colours include white, colourless, cream, pale pink. The usual needle-like, fibrous, radiating habit and vitreous, pearly lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Mesolite forms in or is associated with basalt cavities and low-temperature hydrothermal alteration of volcanic rocks. Important documented localities include India, Iceland, Scotland, Germany, Canada and the United States.
White needle sprays in volcanic cavities
Mesolite is a classic cavity mineral: a dark basalt matrix can carry a cloud of bright white needles that looks almost textile. The spray records slow zeolite growth from fluid moving through once-hot lava.
Collecting and care
Fragile and easily damaged by cleaning; keep dry, supported and away from vibration.
