Caryinite

Chemical formula: NaCaCaMn₂+₂(As₅+O₄)₃

Karynite is a rare sodium, calcium, and manganese arsenate, forming characteristic brown granular aggregates, primarily known from the Långban mine in Sweden.

## Characteristics Karyinite is a rare arsenate mineral belonging to the alluaudite group. It typically forms massive, granular, or nodular aggregates embedded in the host rock. Well-formed crystals are extremely rare and small. The mineral is characterized by a brown, reddish-brown, or yellowish-brown color and is usually opaque or only translucent on thin edges. ## Physical Properties Its Mohs hardness is 3.5-4, making it a relatively soft mineral. It has a vitreous luster, often greasy on fracture. It is a fairly dense mineral, with a specific gravity of approximately 4.22 g/cm³. It exhibits perfect cleavage in one direction. ## Colors and Varieties Brown in various shades, from yellowish to reddish, is dominant. The mineral's name refers to its nutty-brown color. No named color varieties or commercial varieties are distinguished. ## History and Name The name karyinite comes from the Greek word "κάρυον" (karyon), meaning "nut," in reference to its typical color and rounded, granular aggregates. The mineral was first described in 1884 by Hjalmar Sjögren and G. Lindström based on specimens found in the historic Långban mine in Sweden, which remains its type locality. ## Uses Karyinite has no industrial applications. Its significance is purely scientific and collectible, being a prized acquisition for specialists and collectors of rare minerals and those from Långban.

Properties

Mohs hardness: 3.5-4
Luster: Vitreous to Greasy
Streak: Yellowish-brown
Density: 4.22
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Karyinite is identified by its characteristic granular habit, brown color, greasy luster on fracture, and high density. A key diagnostic clue is its origin – almost all specimens come from Långban, Sweden, and are associated with other rare minerals from that deposit. ## Distinguishing from Similar Minerals It can be confused with other brown, massive minerals from Långban, such as berzeliite or sarkinite. Berzeliite is usually lighter (yellow, orange) and crystallizes in the isometric system. Sarkinite has similar hardness but often exhibits a more reddish hue and a different chemical composition. Definitive differentiation often requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Crystals are extremely rare and poorly formed. It almost always occurs as compact, granular, or reniform aggregates embedded in the rock.

Geological environment

## Genesis Karyinite is a product of contact metamorphism in iron and manganese ore deposits. It forms in skarns and metamorphosed carbonate rocks (marbles) under the unique geochemical conditions that prevailed in the Långban deposit. ## Mineral Associations This mineral often occurs in association with other minerals typical of Långban, such as jacobsite, hausmannite, rhodonite, richterite, calcite, and other rare arsenates, e.g., berzeliite. ## Localities The most important and historical locality for karyinite is the Långban mine in the Värmland region of Sweden. This is its type locality and the source of practically all known collectible specimens. Occurrences in other parts of the world are few and uncertain.

Rarity

Very rare

For collectors

## Quality Criteria The most prized karyinite specimens are those that show rich, large aggregates of the mineral with an intense brown color, ideally contrasting with a light host rock (e.g., calcite). Specimens with visible, even if small, crystalline forms have exceptional value. Association with other rare and well-formed minerals from Långban is also of great importance. ## Popular Localities The only significant source of karyinite in the collector's market is the historic Långban mine in Sweden. Specimens from this locality are considered classic and most desirable.

Care and storage

## Cleaning Karyinite specimens should only be dry-cleaned, using a soft brush to remove dust. Due to its arsenic content, wet cleaning should be avoided, as it could lead to the formation of toxic solutions. ## What to Avoid The mineral is sensitive to acids and strong chemicals. As an arsenate, it is toxic – hands should be thoroughly washed after any contact with a specimen. It should be protected from scratching by harder minerals (hardness 3.5-4). It should not be heated or subjected to ultrasound. ## Storage Specimens should be stored in sealed containers or display cases to limit dust accumulation and protect against mechanical damage. It is recommended to store them in separate boxes with a toxicity warning label, away from moisture and direct sunlight.

Sources

IMA Mineral List (CNMNC)