Natrolite

Zeolite-greenland hg

Natrolite-61051

Catapleiite, Natrolite-168971

Natrolite-Inesite-21148

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Natrolite-223955

Natrolite-Inesite-37029

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminum silicate with the chemical formula Na₂Al₂Si₃O₁₀·2H₂O. Natrolite is characterized by its needle-like crystal form and is often found in fibrous, radiating aggregates. It is a relatively common mineral in some geologic environments and is known for its distinctive crystal habit, as well as its physical and chemical properties.

Properties

Natrolite crystals are typically colorless or white, though they can also appear in shades of yellow, red, and green depending on impurities. The mineral has a Mohs hardness of 5 to 5.5, making it relatively soft compared to many other minerals. It has a specific gravity of approximately 2.2, which is considered low, indicating that it is less dense than many other silicate minerals.

The crystal structure of natrolite is characterized by its open framework of silicate and aluminate tetrahedra. This structure allows for the inclusion of water molecules and the exchange of cations, a property that is common among zeolites and contributes to their ability to act as natural ion exchangers.

Formation and Occurrence

Natrolite forms in a variety of geologic settings, most commonly in basaltic and other mafic volcanic rocks. It is often associated with other zeolite minerals and can be found in the cavities and fractures of these rocks, where it crystallizes from alkaline hydrothermal fluids. Natrolite can also occur in metamorphic rocks and as a secondary mineral in granitic rocks.

Significant deposits of natrolite have been found in several parts of the world, including India, Russia, Iceland, and the United States. In these locations, natrolite is often mined for its use in jewelry and as a collector's mineral due to its attractive crystal formations.

Uses and Applications

While natrolite is primarily collected for its aesthetic value, the mineral also has several practical applications. Its ion-exchange properties make it useful in water purification and the removal of contaminants from aqueous solutions. Additionally, natrolite and other zeolites are used in agriculture to improve soil quality and in industry as catalysts in chemical reactions.

See Also

• Zeolite
• Silicate minerals
• Ion exchange
• Geology of India
• Geology of Russia
• Geology of Iceland
• Geology of the United States