Paraberzeliite

Chemical formula: NaCaCaMg₂(As₅+O₄)₃

Paraberzeliite is a rare arsenate of the alluaudite group, forming fine, yellow to orange granular aggregates.

## Characteristics Paraberzeliite is a rare mineral of the alluaudite group, belonging to the arsenate class. It occurs as fine, anhedral (not exhibiting its own crystallographic forms) grains, which form massive aggregates and clusters. Its crystals, if visible, reach sizes up to 0.2 mm. It is usually observed as granular masses filling small spaces in the host rock. ## Physical Properties This mineral is characterized by a vitreous luster. It is brittle, and its fracture is uneven. Due to the small size of the grains, many physical properties are difficult to precisely determine in macroscopic samples. ## Colors and Varieties Paraberzeliite most often takes on a yellow to orange-yellow color. No color varieties or commercial varieties are known. ## History and Name The mineral's name refers to its structural and chemical similarity to berzeliite. The prefix "para-" indicates a different (monoclinic) crystal system compared to the isometric berzeliite. The mineral was first described in 1953 by Paul B. Moore based on material from the Långban mine in Sweden.

Properties

Mohs hardness: 4.5-5
Luster: Vitreous
Streak: Light yellow
Density: 4.12
Cleavage: None
Fracture: Uneven
Transparency: Translucent to opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of paraberzeliite in the field is practically impossible and requires advanced laboratory methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS). In a collection, it may be suspected based on its yellow color, granular form, and co-occurrence with other Långban minerals. ## Distinguishing from Similar Minerals It can be confused with berzeliite, from which it differs in crystal system (monoclinic vs. isometric), which is impossible to determine without specialized equipment. Other yellow arsenates or silicates from the same environment, such as caryinite or magnussonite, may have a similar appearance. ## Crystal Forms It usually forms anhedral, granular aggregates. Poorly formed, small crystals less than 1 mm in size are rarely observed.

Geological environment

## Genesis Paraberzeliite is a mineral of metamorphic origin. It forms as a result of the metamorphism of iron and manganese ore deposits in an arsenic-rich environment. A typical example is skarn deposits, where primary carbonate sediments were transformed at high temperatures. ## Mineral Associations It most often co-occurs with other minerals from the typical Långban paragenesis, such as caryinite, magnussonite, berzeliite, hausmannite, hematite, calcite, and dolomite. ## Localities The only confirmed and classic locality for paraberzeliite is the Långban mine in the Värmland region of Sweden. This is its type locality.

Rarity

Very rare

For collectors

## Quality Criteria The quality of a paraberzeliite specimen primarily depends on the abundance of the mineral on the matrix and the intensity of its color. Since it does not form well-developed crystals, the main criterion is the quantity and visibility of the yellow, granular clusters. Specimens with clear associations with other rare Långban minerals are also more highly valued. ## Popular Localities The only source of collector specimens is the historic Långban mine in Sweden. All specimens available on the market come from this single locality.

Care and storage

## Cleaning It is recommended to clean only with compressed air or a very soft brush. Avoid contact with water and any chemical agents. ## What to Avoid As an arsenate, paraberzeliite is potentially toxic if ingested or inhaled as dust – avoid creating dust and wash hands after contact. Protect it from moisture, acids, and high temperatures. Do not clean it with ultrasound. ## Storage Specimens should be stored in a dry, stable environment, preferably in a closed display box, to avoid dust accumulation and accidental damage. Due to its brittleness, it should be kept away from vibrations.

Sources

IMA Mineral List (CNMNC)