Hermannroseite

Chemical formula: CaCu²⁺(PO₄)(OH)

Hermannroseite is a rare mineral from the adamellite-descloizite group, being a hydrated calcium and copper phosphate with a characteristic grass-green color.

## Characteristics Hermannroseite is a rare secondary mineral belonging to the adamellite-descloizite group. Chemically, it is a hydrated calcium and copper phosphate. It occurs as small, tabular or bladed crystals, rarely exceeding 1 mm in length. It also forms radial aggregates and rosettes. Its most characteristic feature is its vivid, grass-green color. ## Physical properties Hermannroseite crystals are translucent and exhibit a vitreous luster. The mineral's density is approximately 4.08 g/cm³. The hardness has not been precisely determined, but for minerals from the same group, it typically ranges from 4.5 to 5 on the Mohs scale. ## Colors and varieties This mineral occurs in a uniform, grass-green color. No color or commercial varieties have been distinguished. ## History and name The name hermannroseite was given in honor of Hermann Rose (born 1940), a German mineral collector from Stuttgart, specializing in minerals from Tsumeb. The mineral was approved by the International Mineralogical Association (IMA) in 2011, and its description was published in 2012. The type locality is the famous Tsumeb mine in Namibia. ## Applications Due to its extreme rarity and small crystal size, hermannroseite has no industrial applications. It is solely an object of interest for specialized mineral collectors (so-called micromounters) and scientific institutions.

Properties

Luster
Vitreous
Streak
Pale green
Density
4.08
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification Key diagnostic features include its grass-green color, occurrence as small, tabular crystals forming radial aggregates, and a pale green streak. Identification is confirmed by its paragenesis, especially its co-occurrence with other rare copper phosphates and arsenates in the oxidation zones of ore deposits. ## Distinguishing from similar minerals It can be confused with other green secondary copper minerals, such as conichalcite, olivenite, or pseudomalachite. It differs from conichalcite by its often more bladed crystal habit. Olivenite usually forms acicular crystals. Final differentiation requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). ## Crystal forms Crystals are most often flattened, tabular, or bladed. They usually occur as radial or stellate aggregates and rosettes, growing on the host rock.

Geological environment

## Genesis Hermannroseite is a secondary mineral, forming in the oxidation zones (so-called gossans) of polymetallic deposits rich in copper. It forms as a result of the weathering of primary ore minerals in the presence of phosphate-rich solutions. ## Mineral associations In its type locality (Tsumeb), hermannroseite occurs in association with minerals such as ludlockite, schneiderhöhnite, keyite, duftite, anglesite, quartz, and tennantite. ## Localities The only confirmed and described occurrence of hermannroseite in the world is the Tsumeb mine (Ongopolo Mine) in the Oshikoto region of Namibia. This is its type locality.

Rarity

Extremely rare

For collectors

## Quality criteria The most highly prized specimens are those with well-formed, sharp crystals creating aesthetic, radial aggregates. An intense, grass-green color and contrast with the rock matrix are important. Due to the microscopic size of the crystals, specimens are primarily evaluated under magnification. Purity is not a key criterion, but the absence of mechanical damage is highly desirable. ## Popular localities The only source of hermannroseite specimens is the Tsumeb mine in Namibia. Specimens from this historic and now closed mine are highly valued by collectors specializing in rare minerals or minerals from this specific locality.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using a soft brush to remove dust. Due to potential reactivity, the use of water, and especially chemical cleaning agents, is not recommended. ## What to avoid Avoid contact with acids and other chemicals that may damage the mineral. Ultrasonic cleaning and exposure to rapid temperature changes are also not advisable. Store away from moisture. ## Storage As a rare and delicate mineral, hermannroseite should be stored under stable conditions, preferably in a sealed "micromount" box, protecting it from dust, moisture, and mechanical damage. It is not sensitive to light.

External references

Sources

Read more