Lazarenkoite

Chemical formula: CaFe₃+As₃+₃O₇·₃H₂O

Lazarenkoite is a rare calcium and iron arsenate, forming tiny, prismatic crystals with an intense red color and adamantine luster.

## Characteristics Lazarenkoite is a hydrated calcium and iron arsenate. It occurs as very small, prismatic or acicular crystals, rarely exceeding 1 mm in length. It forms radial aggregates, rosettes, or appears as coatings and crusts. Its most characteristic feature is its intense, bright red to orange-red color. ## Physical Properties Lazarenkoite crystals exhibit a strong luster, described as adamantine to resinous. The mineral is transparent to translucent. Due to the small size of the crystals, its hardness and density have not been precisely measured. ## Colors and Varieties This mineral is monochromatic, occurring in shades from bright red to orange-red. No varieties are distinguished. ## History and Name Lazarenkoite was discovered in the Khaidarkan mercury-arsenic deposit in Kyrgyzstan. It was described and approved as a new mineral in 1984. Its name honors Yevgeny Konstantinovich Lazarenko (1912-1979), a Ukrainian mineralogist and former rector of Lviv University. ## Uses Lazarenkoite has no industrial applications. It is solely a mineral of scientific and collector's interest.

Properties

Mohs hardness: 3
Luster: Adamantine, Resinous
Streak: Orange-red
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Key diagnostic features of lazarenkoite include its bright red color, adamantine luster, and characteristic occurrence as tiny, acicular or prismatic crystals forming radial aggregates. It reacts with hydrochloric acid. ## Distinguishing from Similar Minerals It can be confused with other red secondary minerals from oxidation zones, such as realgar or cinnabar. However, realgar is much softer (1.5-2 on the Mohs scale) and often occurs in larger crystals. Cinnabar has a higher density and perfect cleavage. Final differentiation requires advanced analytical methods (XRD, EDS). ## Crystal Forms Lazarenkoite crystallizes as elongated, prismatic or acicular crystals. It most commonly forms radial, stellate, or fibrous aggregates, as well as spherulitic clusters and thin coatings on host rocks.

Geological environment

## Genesis Lazarenkoite is a secondary mineral, formed in the oxidation zones (gossans) of hydrothermal deposits rich in arsenic, especially in mercury-antimony-arsenic deposits. It forms as a result of the weathering of primary arsenic minerals in the presence of limestone or other calcium-rich rocks. ## Mineral Associations This mineral co-occurs with other secondary arsenates and minerals of the oxidation zone. It is most commonly associated with calcite, gypsum, realgar, orpiment, kankite, scorodite, erythrite, annabergite, as well as iron and manganese oxides. ## Localities The most important and type locality for lazarenkoite is the Khaidarkan deposit in the Fergana Valley, Kyrgyzstan. It has also been identified in the Ustarasai mine in Uzbekistan and in small quantities in the Jáchymov mine in the Czech Republic.

Rarity

Very rare

For collectors

## Quality Criteria The most prized lazarenkoite specimens are those with rich, well-formed, radial aggregates of intense, bright red color, contrasting with a light matrix rock. Due to the microscopic size of the crystals, the abundance and aesthetics of the clusters are key, rather than the size of individual needles. Specimens with well-preserved, adamantine luster are more highly valued. ## Popular Localities By far the best and most sought-after specimens come from the type locality - the Khaidarkan deposit in Kyrgyzstan. Material from other localities is much rarer on the collector's market and is primarily of scientific interest.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using compressed air to remove dust. Contact with water is not recommended due to the risk of dissolution or chemical alteration of the mineral. Ultrasonic cleaners should be avoided. ## What to Avoid Avoid all chemicals, acids, and detergents. The mineral is sensitive to moisture and may change under prolonged exposure to air. Protect it from high temperatures and direct sunlight, which can cause fading. ## Storage It is recommended to store specimens in sealed, airtight containers (such as "membrane boxes") or in stable environmental conditions with low humidity. Due to the fragility and small size of the crystals, protect it from shocks and vibrations.

Sources

IMA Mineral List (CNMNC)