Heneuite

Chemical formula: CaMg<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(CO<sub>3</sub>)(OH)

Heneuite is a rare calcium and magnesium phosphate, forming colorless to pale blue, bladed crystals.

## Characteristics Heneuite is a very rare mineral from the phosphate group, chemically a basic calcium and magnesium phosphate and carbonate. It occurs as small, bladed or tabular crystals, usually not exceeding 1 mm in length. The crystals are most often colorless, less frequently pale blue. They typically form disordered aggregates or fan-shaped clusters. ## Physical Properties Heneuite crystals exhibit a vitreous luster and are transparent to translucent. This mineral is characterized by a hardness of 4 on the Mohs scale. Its density is calculated at 3.05 g/cm³. ## History and Name The mineral's name honors Prof. Dr. E. Hene from the University of Göttingen in Germany, in recognition of his contributions to mineralogy and crystallography. Heneuite was approved as a new mineral species by the International Mineralogical Association (IMA) in 1997. It was discovered in a marble quarry near Crestmore Mountain in California, USA.

Properties

Mohs hardness
4
Luster
Vitreous
Streak
White
Density
3.05
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Triclinic

Diagnostic features

## Identification Amateur identification of heneuite is practically impossible due to its small size and occurrence. Recognition requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). Visually, it is characterized by small, bladed, colorless or pale blue crystals. ## Distinguishing from Similar Minerals It can be confused with other rare phosphates occurring in similar environments, such as johnsomervilleite. Definitive differentiation is only possible based on detailed laboratory analyses. ## Crystal Forms It forms elongated, bladed or flattened, tabular crystals. It often occurs as radial or fan-shaped aggregates, as well as disordered clusters on the surface of the host rock.

Geological environment

## Genesis Heneuite forms as a result of hydrothermal processes occurring within skarns, at the contact of a quartz monzonite intrusion with Precambrian marbles (carbonate rocks metamorphosed at high temperatures). ## Mineral Associations It co-occurs with minerals such as magnesite, dolomite, brucite, hydroxylapatite, johnsomervilleite, sapphirine, and monticellite. ## Localities The only confirmed locality for heneuite in the world is its type locality – the Commercial quarry in the Crestmore area, Riverside County, California, USA.

Rarity

Very rare

For collectors

## Quality Criteria As a "micromount" type mineral, specimens with well-formed, sharp, and undamaged crystals, ideally forming aesthetic, fan-shaped aggregates, are most highly valued. Specimens with a pale blue coloration, which is rarer than colorless, are also desirable. Contrast with the surrounding host rock also enhances visual appeal. ## Popular Localities All known collector specimens originate from a single location worldwide: the Commercial quarry in Crestmore, California, USA. This makes every specimen from this locality extremely valuable to collectors specializing in rare minerals or minerals from specific localities.

Care and storage

## Cleaning Due to its rarity and delicacy, mechanical cleaning is not recommended. If absolutely necessary, compressed air can be used to remove dust. Avoid contact with water and chemicals. ## What to Avoid Avoid ultrasonics, steam cleaning, and all acids and bases, which can damage the mineral. Due to the presence of a carbonate group, it is sensitive to acids. Store away from heat sources. ## Storage Heneuite specimens should be stored under stable conditions, in a sealed "micromount" box, to protect them from dust, mechanical damage, and sudden temperature changes.

Sources

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