Whiteite-(CaMgMg)

Chemical formula: CaMg₃Al₂(PO₄)₄(OH)₂·8H₂O

A colorless, hydrated phosphate from the whiteite group, forming small, tabular crystals with a vitreous luster.

## Characteristics Whiteite-(CaMgMg) is a hydrated calcium, magnesium, and aluminum phosphate, belonging to the whiteite subgroup within the jahnsite group. This mineral forms very small, usually not exceeding 1 mm, tabular or bladed crystals. They are colorless and transparent, with a vitreous luster. Due to the small size of the crystals, its macroscopic features are difficult to observe without magnification. ## Physical Properties Whiteite-(CaMgMg) has a hardness of 4 on the Mohs scale, classifying it as a relatively soft mineral. Its density is approximately 2.48 g/cm³. The crystals are transparent and have a vitreous luster. It exhibits perfect {001} cleavage. ## Colors and Varieties This mineral is colorless. No colored or commercial varieties are distinguished. ## History and Name Whiteite-(CaMgMg) was first described in 1978 by William S. Wise. Its name honors John Sampson White (born 1933), an American mineralogist and curator of the mineralogical collection at the Smithsonian Institution. The suffix "(CaMgMg)" specifies the chemical composition of the mineral according to the naming rules within the jahnsite group, indicating the dominant cations in specific structural positions.

Properties

Mohs hardness
4
Luster
Vitreous
Density
2.48
Cleavage
on {001}
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Amateur identification of whiteite-(CaMgMg) is practically impossible due to its rarity and microscopic crystal size. It requires advanced analytical techniques, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). A characteristic feature, visible under a microscope, is the tabular habit of colorless crystals. ## Distinguishing from Similar Minerals It can be confused with other minerals from the jahnsite-whiteite group, such as jahnsite-(CaMnMg) or whiteite-(MnFeMg). Differentiation is possible only based on precise chemical analysis. Visually, it may resemble other microscopic, colorless phosphates or silicates occurring in similar environments. ## Crystal Forms Crystals are very small, usually tabular in habit, flattened parallel to the {001} plane. They occur as single, dispersed crystals or small, loose aggregates on the surface of the host rock.

Geological environment

## Genesis Whiteite-(CaMgMg) is a secondary mineral, formed in complex granitic pegmatites. It forms as a result of hydrothermal processes or weathering, which lead to the alteration of earlier phosphate minerals in the presence of solutions rich in calcium, magnesium, and aluminum. ## Mineral Associations This mineral coexists with other phosphates, such as wardite, natrowardite, montgomeryite, collinsite, as well as quartz, microcline, and muscovite. ## Localities The most important and type locality (localitas typica) is the Argentum Mining Co. mine (also known as Northern Belle Mine) in the Candelaria district, Mineral County, Nevada, USA. This is the only confirmed and well-documented locality for this mineral worldwide.

Rarity

Very rare

For collectors

## Quality Criteria As a microscopic mineral, whiteite-(CaMgMg) is primarily valued by specialized collectors (so-called micromounters). The value of a specimen is determined by the presence of well-formed, sharp crystals, their transparency, and the abundance of occurrence on the rock matrix. Association with other rare phosphates is also important. ## Popular Localities The only source of collector specimens is the type locality in Nevada, USA. Specimens from this location are extremely sought after due to their rarity and status as type material.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to its softness and potential reactivity, contact with water and any chemical agents should be avoided. ## What to Avoid Avoid ultrasonic cleaners, strong detergents, acids, and solvents. The mineral is relatively soft, so it must be protected from scratching by harder minerals. As a hydrated mineral, it can be sensitive to high temperatures, which may lead to dehydration and structural damage. ## Storage It is recommended to store specimens in stable conditions, away from heat sources and direct sunlight. The safest way is to keep them in sealed collector boxes, which protects them from dust, mechanical damage, and sudden changes in humidity.

External references

Sources

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