Sarkinite
Chemical formula: Mn²⁺₂(AsO₄)(OH)
Sarkinite is a rare manganese arsenate mineral, typically forming small, pink to red crystals, often found in metamorphic deposits.
Description
## Characteristics Sarkinite is a rare mineral belonging to the arsenate group. It typically occurs as small, prismatic or tabular crystals, often forming radial or granular aggregates. Its color ranges from pink, through red, to yellowish-red, which gives it a characteristic appearance. It is a brittle mineral with a distinct vitreous to resinous luster. ## Physical Properties The Mohs hardness of sarkinite is 4-5. This mineral has a specific gravity of approximately 4.08 g/cm³. It exhibits distinct cleavage along the {100} plane. The fracture is uneven. Sarkinite is transparent to translucent. ## Colors and Varieties Sarkinite occurs in shades of red, pink, yellowish-red, as well as yellow and reddish. In transmitted light, it can be light pink or yellow. No specific commercial or color varieties are distinguished beyond natural color variations. ## History and Name Sarkinite was discovered in 1885. Its name comes from the Greek word "sarcinos," meaning "fleshy," which likely refers to its color and appearance. This mineral was first described from the Swedish deposit of Långban. ## Uses Sarkinite has no industrial uses due to its rarity and small crystal size. It is valued exclusively by mineral collectors.
Diagnostic features
## Identification Sarkinite can be identified by its characteristic color (pink, red, yellowish-red), vitreous to resinous luster, and typical crystal forms. It often occurs in radial or granular aggregates. A hardness of 4-5 on the Mohs scale is also a diagnostic feature. ## Distinguishing from Similar Minerals Sarkinite can be confused with other manganese minerals of similar color, such as rhodonite or rhodochrosite. It differs from rhodonite by its lower hardness and different cleavage. It differs from rhodochrosite by its lack of reaction with acids and different crystal form. The streak color (red to yellow) is also an important diagnostic feature. ## Crystal Forms Sarkinite forms monoclinic crystals, usually prismatic or tabular. It often occurs as radial, granular, or massive aggregates.
Geological environment
## Genesis Sarkinite is a secondary mineral, forming in the oxidation zones of manganese deposits, especially in arsenic-rich environments. It typically occurs in metamorphic deposits where arsenic and manganese are present in the host rocks. ## Mineral Associations Sarkinite often co-occurs with other manganese and arsenic minerals, such as hausmannite, braunite, manganite, arsenopyrite, as well as calcite and quartz. ## Localities The most important sarkinite localities are in Sweden, especially in the famous Långban deposit. Other known occurrences include Germany (Eisleben), Japan (Hyōgo Prefecture), and the United States (New Jersey).
Rarity
Rare
Collector aspects
## Quality Criteria The most prized sarkinite specimens are those that exhibit well-formed, distinct crystals with intense, uniform color (especially pink or red). Crystal size, transparency, and absence of mechanical damage also influence collector value. Specimens with aesthetic associations with other minerals are also highly valued. ## Popular Localities The most sought-after sarkinite specimens come from Långban, Sweden, which is the classic locality for this mineral. Specimens from this locality are often a benchmark for collectors due to their quality and aesthetics.
Care and storage
## Cleaning Sarkinite is a relatively soft mineral, so it should be handled with care. For cleaning, it is best to use a soft brush and lukewarm water. The specimen can be gently rinsed under running water, then dried with a soft cloth or left to air dry. ## What to Avoid Avoid using strong chemicals, acids, and detergents, which can damage the mineral's surface or alter its color. Sarkinite is sensitive to high temperatures, so it should not be exposed to direct sunlight for extended periods or to sudden temperature changes. Due to its arsenic content, it is recommended to avoid direct contact with the mouth and to wash hands after handling the specimen. ## Storage Sarkinite is best stored in closed display cases or boxes, away from dust and moisture. Due to its softness, avoid storing it with harder minerals that could scratch it. Ideal storage involves individual specimens in separate, soft containers or on a soft pad.