Smamite

Chemical formula: Ca₂Sb₅+(OH)₄[H(As₅+O₄)₂]·₆H₂O

Smamite is a very rare hydrated calcium antimony arsenate, forming colorless, tabular crystals with a pearly luster.

## Characteristics Smamite is a mineral from the arsenate group, characterized by a complex chemical composition including calcium, antimony, arsenic, and water. It occurs as very small, tabular or bladed crystals, reaching sizes up to 0.2 mm. The crystals are colorless and transparent, often forming small, radial aggregates or rosettes. Due to their small size, visual features are usually only discernible under a microscope. ## Physical Properties Smamite crystals exhibit a hardness of approximately 2 on the Mohs scale, making them a very soft mineral. They have a pearly luster on cleavage surfaces and a vitreous luster elsewhere. The mineral is transparent. The density calculated based on the formula and unit cell parameters is 3.03 g/cm³. ## History and Name The mineral's name comes from the acronym SMAM (Staatliches Museum für Mineralogie und Geologie, Dresden, Germany), where the first studies on this mineral were conducted. Smamite was approved as a new mineral species by the International Mineralogical Association (IMA) in 2013. It was discovered in the Gebel el Hamam mine in the South Sinai region of Egypt.

Properties

Mohs hardness: 2
Luster: Pearly
Streak: White
Density: 3.03
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent
Crystal system: Triclinic

Diagnostic features

## Identification Amateur identification of smamite is practically impossible due to the microscopic size of the crystals and its occurrence in complex parageneses. Definitive identification requires advanced analytical techniques, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). Visually, under high magnification, characteristic colorless, tabular crystals with a pearly luster can be observed. ## Distinguishing from Similar Minerals Smamite can be confused with other secondary arsenate and antimonate minerals, such as gypsum, pharmacolite, or various minerals from the apatite group, which can form similar colorless coatings or small crystals. Key to differentiation is its co-occurrence with other rare arsenates in a specific geological environment and confirmation of the presence of antimony and arsenic through chemical analysis. ## Crystal Forms Smamite crystallizes as thin, tabular crystals with a hexagonal or rhombic outline, elongated in one direction. Crystals often combine into small, radial or fan-shaped aggregates and rosettes.

Geological environment

## Genesis Smamite is a secondary mineral, forming in the oxidation zones (gossans) of polymetallic deposits. It forms as a result of weathering and alteration of primary minerals containing arsenic, antimony, and calcium under low temperature and pressure conditions. Its formation is associated with hydrothermal solution activity. ## Mineral Associations This mineral occurs in association with other rare, secondary arsenates and sulfates. In its type locality (Gebel el Hamam), its co-occurrence with pharmacolite, gypsum, hematite, quartz, lavendulan, erythrite, annabergite, and other unidentified arsenates has been noted. ## Localities The only confirmed locality for smamite in the world is its type locality: the Gebel el Hamam mine, Sinai Peninsula, in the South Sinai Governorate, Egypt. This site is known for the occurrence of many rare secondary minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria As a microscopic mineral (micromount), the collector's value of smamite is determined by the quality and richness of crystal aggregates on the rock matrix. The most desirable specimens are those with well-formed, sharp crystals forming distinct, radial or rosette-like clusters. Aesthetic composition with other color-contrasting associated minerals, e.g., pink erythrite or blue lavendulan, is also important. The purity and transparency of individual crystals, visible under a microscope, also increase the specimen's value. ## Popular Localities The only source of smamite specimens is the Gebel el Hamam mine in Egypt. Material from this locality is extremely rare on the collector's market and sought after by specialists in rare and systematic minerals.

Care and storage

## Cleaning Smamite specimens are extremely delicate and small, so mechanical cleaning is not recommended. Any attempts to use brushes, or even a stream of water, can irreversibly destroy the crystals. If cleaning is absolutely necessary, compressed air can be carefully used from a safe distance. ## What to Avoid Avoid contact with all chemicals, including acids and bases. The mineral is very soft (hardness 2), so it is susceptible to scratches and mechanical damage. It should be protected from high temperatures, which can lead to dehydration and destruction of the crystal structure. Due to its fragility, vibrations and shocks should be avoided. ## Storage Smamite must be stored under stable conditions, preferably in a closed, padded "micromount" box, to protect it from dust, moisture, and physical damage. Display should only take place in specialized display cases, away from heat sources and direct sunlight.

Sources

IMA Mineral List (CNMNC)