Destinezite
Chemical formula: Fe<sup>3+</sup><sub>2</sub>(PO<sub>4</sub>)(S<sup>6+</sup>O<sub>4</sub>)(OH)·6H<sub>2</sub>O
Destinezite is a rare, hydrated iron sulfophosphate, forming small, yellowish or greenish crystals and aggregates in the oxidation zones of ore deposits.
Properties
- Mohs hardness
- 3.5
- Luster
- Vitreous, Pearly
- Streak
- White to pale yellow
- Density
- 2.45-2.54
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
Diagnostic features
## Identification Destinezite is difficult to identify visually without specialized equipment. Its characteristic features include its occurrence as small, yellowish or greenish aggregates and crusts in oxidation zones. It reacts with hydrochloric acid. Certain identification requires advanced methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other secondary iron phosphates and sulfates, such as cacoxenite, diadochite, strengite, or jarosite. Diadochite is its amorphous counterpart and often co-occurs with it or forms as a result of its dehydration. Distinguishing it from these minerals based on macroscopic features is often impossible. ## Crystal Forms Crystals are very small, tabular or bladed, often flattened parallel to {010}. They form characteristic radial or rosette-like aggregates, as well as fibrous, earthy, and massive crusts.
Geological environment
## Genesis Destinezite is a secondary mineral, forming in the oxidation (weathering) zones of ore deposits, especially pyrite and marcasite. It forms in an environment rich in iron, sulfates (derived from sulfide decomposition), and phosphates (released from sedimentary rocks, e.g., phosphorites, or primary minerals like apatite). It is a typical mineral for acidic mine waters. ## Mineral Associations It often co-occurs with other secondary minerals of the oxidation zone, such as diadochite (its amorphous polymorph), delvauxite, gypsum, evansite, strengite, vivianite, melanterite, as well as limonite and goethite. ## Localities Important localities worldwide include Argenteau, Belgium (type locality); various locations in the Czech Republic (e.g., Stříbro, Chvaletice); in Germany (Saxony, Thuringia); in Romania (Sacarâmb); in the USA (California, Nevada). In Poland, its occurrence has been reported in the Świętokrzyskie Mountains (Wiśniówka).
Rarity
Rare
For collectors
## Quality Criteria Specimens with visible, well-formed microcrystals forming aesthetic, radial or rosette-like aggregates are most valued by collectors. A contrasting rock matrix and an intense, pure color (e.g., vivid yellow) enhance the attractiveness of the specimen. Due to the microscopic size of its crystals, destinezite is primarily of interest to micromounters. ## Popular Localities Classic and prized specimens come from historical localities in Belgium (Argenteau) and the Czech Republic. Specimens from these locations have historical and scientific significance.
Care and storage
## Cleaning Destinezite specimens should only be cleaned mechanically, using a soft brush to remove dust and loose contaminants. Due to its reactivity and solubility, contact with water, and especially with acids and other chemicals, should be avoided. ## What to Avoid Destinezite is sensitive to moisture and can undergo dehydration (loss of water) in dry environments or under heat, leading to its transformation into diadochite. It should be protected from direct sunlight, high temperatures, and all liquids. Ultrasonic cleaners must not be used. ## Storage It is recommended to store specimens in stable humidity conditions, preferably in sealed, airtight containers (e.g., "membrane boxes") or in display cases away from sources of heat and light. Avoid storage in damp basements or on sunny windowsills.