Sulfatoredmondite

Chemical formula: [Pb²⁺₈O₂Zn²⁺(OH)₆](S⁶⁺O₄)₄·6H₂O

Sulfatoredmondite is a rare, hydrated lead zinc sulfate, distinguished by its occurrence as microscopic, colorless crystals.

## Characteristics Sulfatoredmondite is a very rare mineral from the sulfate group, chemically classified as a hydrated lead zinc sulfate with additional oxide and hydroxide anions. It occurs as very small, tabular or bladed crystals, rarely exceeding 0.2 mm in length. It typically forms small, scattered aggregates or coatings. Due to the microscopic size of its crystals, its visual features are difficult to observe without specialized equipment. ## Physical Properties This mineral is characterized by low hardness, approximately 2 on the Mohs scale, meaning it is very soft and susceptible to scratching. Its density is relatively high at 5.173 g/cm³, which is typical for lead-bearing minerals. The crystals are transparent. ## Colors and Varieties Sulfatoredmondite is colorless. No colored varieties or trade names are known. ## History and Name The mineral's name refers to its chemical composition (sulfate) and its discovery location – the Redmond mine in North Carolina, USA. It was formally described as a new mineral species relatively recently, and its name honors both the type locality and the dominant anion in its structure.

Properties

Mohs hardness
2-0
Streak
white
Density
5.173
Fracture
Irregular/Uneven
Transparency
Transparent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of sulfatoredmondite is impossible without advanced laboratory techniques such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). In collector conditions, identification relies solely on a label from a reliable source confirming prior scientific research. Visually, these are just microscopic, colorless crystals on the host rock. ## Distinguishing from Similar Minerals Due to its microscopic nature, sulfatoredmondite can be confused with many other secondary sulfate or carbonate minerals, such as anglesite, cerussite, or hydrocerussite, which often form similar coatings. Definitive differentiation is only possible through chemical and structural analysis. ## Crystal Forms Sulfatoredmondite forms very small, elongated crystals with a bladed or tabular habit. These crystals rarely occur individually, more often forming small, scattered aggregates or tangled clusters on the surface of the host rock.

Geological environment

## Genesis Sulfatoredmondite is a secondary mineral, forming in the oxidation (weathering) zones of polymetallic deposits rich in lead and zinc. It forms as a result of reactions between sulfate-bearing waters and primary ore minerals such as galena and sphalerite. Its formation is limited to very specific chemical conditions. ## Mineral Associations At the type locality, sulfatoredmondite co-occurs with other secondary lead and zinc minerals such as anglesite, cerussite, hydrocerussite, hemimorphite, as well as quartz and other gangue minerals. ## Localities The only confirmed and described occurrence of sulfatoredmondite in the world is its type locality – the Redmond mine, located near Waterville Lake in Haywood County, North Carolina, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of sulfatoredmondite specimens is primarily assessed based on the richness and abundance of microscopic crystals on the rock matrix. Since this mineral is available exclusively as a "micromount," specimens with clearly visible, well-formed crystals under magnification are most desirable. Association with other rare secondary minerals is also important. ## Popular Localities The only source of sulfatoredmondite specimens is the Redmond mine in North Carolina, USA. All specimens available on the collector's market originate from this single locality.

Care and storage

## Cleaning Due to its extreme rarity, small size, and low hardness, sulfatoredmondite specimens are practically not subject to cleaning. Any attempts at mechanical or chemical cleaning can irreversibly destroy the delicate crystals. Specimens should be left in their untouched state, as they were found. ## What to Avoid Avoid contact with any chemicals, including water. Temperature and humidity changes can be harmful. The mineral is very soft, so touching, vibrations, and any mechanical interactions should be avoided. ## Storage Sulfatoredmondite specimens should be stored exclusively in specialized, sealed "micromount" containers that protect them from dust, moisture, and mechanical damage. Storage under stable room conditions is crucial for preserving the integrity of these rare specimens.

External references

Sources

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