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Occurs in Pinal County.

Analcite. Al Copley photo
Analcite. Al Copley photo

Chemical Formula: Na(AlSi2O6)·H2O

Specific Gravity: 2.2-2.3

Luster: Vitreous to greasy

Hardness: 5.5-6

Analcime, also called analcite, is a zeolite mineral that forms in cavities and fractures of volcanic rocks. It usually occurs as colorless, white, or grayish crystals and is known for its characteristic cubic crystal habit.

Next Pinal County mineral: Andalusite

MinDat Analcime

Analcime is a mineral that belongs to the zeolite group, which consists of porous and hydrated minerals with a three-dimensional framework structure. Analcime is recognized for its distinctive crystal habit, which often forms well-defined trapezohedral crystals with 12 rhombic faces. The name “analcime” is derived from the Greek words “an” (not) and “alkimos” (strong), referencing the mineral’s relatively low hardness.

The chemical formula for analcime is typically written as Na(AlSi2O6)•H2O, indicating its composition of sodium (Na), aluminum (Al), silicon (Si), oxygen (O), and water molecules (H2O). Analcime crystals often contain cavities or voids that can be filled with water or other fluids.

Analcime is commonly found in volcanic rocks, especially those that have undergone alteration processes. It forms under low-temperature and low-pressure conditions, typically during the later stages of hydrothermal alteration. The mineral can develop from the alteration of other minerals like feldspars and volcanic glass.

One of the notable properties of analcime is its ability to undergo reversible dehydration and rehydration. When heated, analcime releases its water molecules and transforms into a dehydrated form known as “pseudoanalcime.” Upon rehydration, pseudoanalcime can revert back to analcime.

Geologically, the presence of analcime can be indicative of specific alteration environments and can provide insights into the conditions under which the host rock was altered. Analcime can also serve as a source of valuable information about volcanic processes and the hydrothermal history of a region.

Due to its attractive crystal form and unique properties, analcime is sometimes used as a mineral specimen by collectors. Its role in scientific research and its association with various geological processes make it significant in the fields of geology and mineralogy.

In summary, analcime is a zeolite mineral known for its trapezohedral crystal habit and reversible dehydration properties. It forms in volcanic rocks during alteration processes and provides insights into geological conditions and processes.