Parascorodite

Chemical formula: Fe³⁺As⁵⁺O₄(H₂O)₂

Parascorodyte is a hydrated iron arsenate, a rare secondary mineral with a vitreous luster, and a polymorph of scorodite.

## Characteristics Parascorodyte is a hydrated iron(III) arsenate, chemically identical to scorodite but crystallizing in a different crystallographic system (it is its polymorph). It occurs as very fine, hexagonal crystals that form aggregates resembling powder or dusty coatings. Due to the small size of the crystals, its macroscopic features are difficult to observe without magnification. ## Physical Properties This mineral is characterized by very low hardness, ranging from 1 to 2 on the Mohs scale, which means it is extremely soft and susceptible to scratching. It has a vitreous luster, and its streak is yellowish-white. It is translucent. ## Colors and Varieties Parascorodyte is usually white. No color varieties or commercial varieties are distinguished. ## History and Name The mineral's name refers to its polymorphic relationship with scorodite (Greek: *para* - beside, near). It was first described by Petr Ondruš and co-workers in 1997. The type locality (locus typicus) was identified as deposits in the Kaňk area, near Kutná Hora in the Czech Republic. ## Uses Due to its rarity and inconspicuous occurrence, parascorodyte has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals or minerals from specific localities.

Properties

Mohs hardness: 1-2
Luster: Vitreous
Streak: Yellowish white
Density: 0
Transparency: Translucent
Crystal system: Hexagonal

Diagnostic features

## Identification Identifying parascorodyte based on visual characteristics is practically impossible without specialized equipment. Recognition requires advanced analytical methods, such as X-ray diffraction (XRD) to confirm the hexagonal crystal structure, and chemical analysis (e.g., EDS) to verify the composition. Its occurrence as dusty, white coatings in the oxidation zones of arsenical deposits is an indication, but not a diagnostic feature. ## Distinguishing from Similar Minerals Macroscopically, it is indistinguishable from many other secondary arsenates and sulfates that form dusty coatings, such as pharmacolite, gypsum, or other polymorphs of iron arsenate. Key to differentiation is the examination of the crystal structure – scorodite crystallizes in the orthorhombic system, while parascorodyte crystallizes in the hexagonal system. ## Crystal Forms It forms very fine, microscopic crystals with a habit of hexagonal tablets or plates. These crystals usually occur as loose, dusty or earthy aggregates and coatings.

Geological environment

## Genesis Parascorodyte is a secondary mineral, forming in the oxidation (weathering) zones of ore deposits rich in arsenic, especially arsenopyrite. It forms under low-temperature conditions as a result of the weathering of primary minerals containing arsenic and iron. ## Mineral Associations It co-occurs with other secondary minerals of the oxidation zone. In the type locality (Kaňk, Czech Republic), it was found in association with pitticite, bukovskýite, gypsum, jarosite, and iron oxides such as goethite. ## Localities This is a very rare mineral, known from only a few locations worldwide. Besides the type locality in Kaňk near Kutná Hora in the Czech Republic, its occurrence has also been reported in the Hemerdon mines (Devon, England) and Poldice (St Day, Cornwall, England).

Rarity

Very rare

For collectors

## Quality Criteria The quality of parascorodyte specimens is primarily assessed based on the abundance of its occurrence on the rock matrix and the confirmation of its identity through analysis. Since the crystals are microscopic, their individual form is not of great importance. The most prized specimens are those from the type locality, with clearly visible, abundant coatings on a small matrix. ## Popular Localities By far the most valued and sought-after specimens by collectors come from the mineral's discovery site – the Kaňk region in the Czech Republic. These are considered classic examples of this mineral.

Care and storage

## Cleaning Parascorodyte specimens are extremely delicate and sensitive. Mechanical cleaning is highly inadvisable. If necessary, compressed air can be used from a safe distance to remove loose dust particles. Contact with water should be avoided. ## What to Avoid The mineral is very soft (hardness 1-2 on the Mohs scale), so any contact with harder objects, friction, or pressure should be avoided. It should be protected from moisture, chemicals, and ultrasound. Due to its nature, it should not be exposed to high temperatures. ## Storage Specimens should be stored in stable conditions, in closed, padded "micromount" boxes to protect them from mechanical damage, dust, and humidity changes. Display should be away from sources of vibration.