Orthoserpierite

Chemical formula: CaCu²⁺₄(S⁶⁺O₄)₂(OH)₆·₃H₂O

Orthoserpierite is a rare secondary mineral from the devilline group, forming delicate, acicular crystals of a characteristic blue color.

## Characteristics Orthoserpierite is a hydrated calcium copper sulfate belonging to the devilline group. It occurs as very small, acicular or bladed crystals, which often form delicate, radial aggregates, crusts, or rosettes. Due to the small size of the crystals, its features are most often observed under magnification. Typical specimens appear as thin coatings on host rocks. ## Physical Properties Orthoserpierite crystals are very brittle and delicate. This mineral is characterized by a vitreous luster and a pale green streak. Its density is approximately 3.00 g/cm³. ## Colors and Varieties Orthoserpierite occurs in a uniform, characteristic blue or bluish-green color. No color or commercial varieties are distinguished. ## History and Name The mineral's name refers to its orthorhombic (ortho-) crystallographic symmetry and its resemblance to serpierite, to which it is closely related. It was described as a new mineral species in 1985. ## Applications Orthoserpierite has no industrial applications. It is solely a mineral of scientific and collecting interest, valued by specialists collecting rare secondary copper minerals.

Properties

Luster: Vitreous
Streak: Light green
Density: 3.00
Fracture: Splintery
Transparency: Translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Orthoserpierite is identified by its characteristic blue color, acicular crystal habit forming radial aggregates, and occurrence in the oxidation zones of copper deposits. Due to the small size of the crystals, final identification often requires chemical or crystallographic analysis. ## Distinguishing from Similar Minerals It can be confused with other secondary copper minerals of similar color and form, such as serpierite, devilline, brochantite, malachite, azurite, gypsum, smithsonite, or hemimorphite. Distinguishing it from serpierite, which crystallizes in the monoclinic system, is impossible without advanced studies. It differs from devilline by the presence of calcium in its chemical composition. ## Crystal Forms It forms very small, elongated, acicular or bladed crystals. Most often, they occur as radial or tangled aggregates, as well as thin crusts and coatings on rock surfaces.

Geological environment

## Genesis It is a secondary mineral, formed in the oxidation (weathering) zones of polymetallic ore deposits, mainly copper. It forms as a result of reactions of sulfate-rich waters with copper ore minerals in the presence of calcium-rich rocks, such as limestones or dolomites. ## Mineral Associations It often co-occurs with other secondary sulfate and carbonate minerals, such as serpierite, devilline, brochantite, malachite, azurite, gypsum, smithsonite, or hemimorphite. ## Localities The most important localities for this rare mineral are in France (Chessy mines, discovery site), Greece (Lavrion), Germany (Baden-Württemberg), Italy (Sardinia), Austria (Carinthia), and the USA (Arizona, Nevada).

Rarity

Rare

For collectors

## Quality Criteria The most valued orthoserpierite specimens are those with well-formed crystals, visible under magnification, forming aesthetic, radial aggregates of intense blue color. Contrast with the rock matrix and the presence of rare associated minerals are also important. Due to the microscopic size of the crystals, specimens are primarily evaluated based on the richness and aesthetics of the aggregates. ## Popular Localities The localities in Lavrion, Greece, and Chessy, France, are considered classic and yield the best specimens. Specimens from these locations are the benchmark for this mineral.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Any contact with water or a brush can irreversibly damage the delicate crystals. Ultrasonic cleaning is not recommended. ## What to Avoid Avoid contact with water, acids, and all chemical agents. The mineral is very brittle, so it must be protected from impacts, vibrations, and abrasion. Prolonged exposure to moisture can lead to its degradation. ## Storage Orthoserpierite specimens should be stored in sealed, stable containers (e.g., "micromount" type), protected from dust, moisture, and mechanical damage. Do not expose it to direct sunlight.

External references

https://www.mindat.org/min-3031.html