Parthéite

Chemical formula: Ca₂(Si₄Al₄)O₁₅(OH)₂·₄H₂O

Partheite is a rare zeolite group mineral, forming delicate, needle-like white crystals, discovered in Turkey.

## Characteristics Partheite is a hydrated calcium aluminosilicate belonging to the zeolite group. It occurs as delicate, fibrous or radial aggregates, which can form felt-like or cotton-like masses. Individual crystals are elongated needles or blades, reaching several centimeters in length, although they are usually much smaller. Due to its structure, it is a very brittle and delicate mineral. ## Physical Properties Partheite crystals are characterized by a Mohs hardness of 4. They have a vitreous luster, which can be pearly on fracture surfaces. They are transparent, and their density is approximately 2.39 g/cm³. They exhibit perfect cleavage in two directions. ## Colors and Varieties This mineral is usually white. In transmitted light, it becomes colorless. No colored varieties have been distinguished. ## History and Name Partheite was first described in 1979 by W. Sarp, J. Deferne, H. Bizouard, and B. W. Liebich. Its name honors Erwin Parthé (1919–2006), a professor of crystallography at the University of Geneva, for his contributions to crystal structure research. The type locality is Belenköysirti Hill in Burdur Province, Turkey. ## Uses Partheite has no industrial applications. It is solely an object of interest for collectors of rare minerals and scientific institutions.

Properties

Mohs hardness: 4
Luster: Vitreous, pearly
Streak: White
Density: 2.39
Cleavage: on {100}, {110}
Fracture: Uneven
Transparency: Transparent
Crystal system: Monoclinic

Diagnostic features

## Identification Partheite can be identified by its characteristic form – it creates white, very delicate, needle-like or fibrous aggregates, often with a radial structure. Low hardness (4 on the Mohs scale) and brittleness are also important features. It occurs in a specific geological environment, which aids in identification. ## Distinguishing from Similar Minerals It can be confused with other fibrous zeolites, such as natrolite, mesolite, or scolecite. Differentiation usually requires advanced research methods, such as X-ray diffraction (XRD), due to visual similarity and physical properties. Compared to many other zeolites, partheite is much rarer. ## Crystal Forms Crystals are strongly elongated, needle-like or bladed, parallel to the crystallographic b-axis. They form radial, stellate, or fibrous aggregates, as well as disordered, felted masses.

Geological environment

## Genesis Partheite is a secondary mineral, formed by low-temperature hydrothermal processes. In its type locality (Turkey), it occurs in ophiolites, filling fractures in rodingites – rocks formed by metasomatism of gabbroic rocks. It is a product of plagioclase alteration. ## Mineral Associations This mineral co-occurs with other minerals typical of rodingite environments. It is most often accompanied by prehnite, augite, thomsonite-(Ca), and chlorites. ## Localities The main and most known occurrence of partheite is its type locality: Belenköysirti Hill in Yeşilova district, Burdur Province, Turkey. This is the only place from which well-formed, collectible specimens originate. The mineral has also been identified in gabbros in the ophiolite massif near Sestri Levante in Italy and in the Chenaillet complex in the Cottian Alps in France, however, specimens from these locations do not match the quality of the Turkish ones.

Rarity

Very rare

For collectors

## Quality Criteria The most valued partheite specimens are those that form well-defined, radial aggregates composed of long, undamaged needles. Contrast with a dark matrix significantly enhances visual appeal. Purity of white color and lack of impurities are also important. Due to extreme brittleness, undamaged specimens are rare and command higher prices. ## Popular Localities The only source of valuable collector specimens is the type locality in Turkey (Belenköysirti Hill, Doganbaba). Specimens from this location are the standard for this mineral in the collector's market.

Care and storage

## Cleaning Partheite specimens are extremely delicate and brittle. Mechanical cleaning should be avoided. If absolutely necessary, compressed air can be used from a safe distance to remove loose dust. Contact with water, especially deionized water, can be risky due to its zeolite nature. ## What to Avoid Contact with acids and other chemicals must be strictly avoided. The mineral is sensitive to high temperatures, which can cause dehydration and destruction. It should be protected from shocks, impacts, and any pressure. ## Storage It is recommended to store specimens in tightly sealed, padded "micromount" boxes to protect them from dust, mechanical damage, and humidity changes. Do not expose it to direct sunlight or places with fluctuating temperatures.