Sweetite

Chemical formula: Zn<sup>2+</sup>(OH)<sub>2</sub>

Sweetite is a rare zinc mineral, forming tiny, colorless or white crystals with a tetragonal structure.

## Characteristics Sweetite is a hydrated zinc hydroxide, occurring as small, well-formed crystals. It typically forms isolated, dipyramidal crystals with sharp edges, reaching up to 1.5 mm in size. It is a transparent to translucent mineral with a vitreous luster. Due to its small size and rarity, it is primarily valued by specialized collectors. ## Physical Properties Sweetite crystals are brittle. The mineral has a hardness of approximately 3 on the Mohs scale and a density close to 3.35 g/cm³. It does not exhibit fluorescence under ultraviolet light. ## Colors and Varieties Sweetite is most often colorless, less frequently white or pale cream. No color varieties or commercial varieties are distinguished. ## History and Name The mineral was discovered in the Milltown Quarry in Derbyshire, England, and described in 1984. Its name honors Jessie May Sweet (1901-1986), a British mineralogist and curator of collections at the British Museum (Natural History), in recognition of her contributions to the study of British minerals. ## Applications Sweetite has no industrial applications. Its significance is purely scientific and as a collector's item.

Properties

Mohs hardness
3
Luster
Vitreous
Streak
White
Density
3.35
Cleavage
Imperfect on {101}
Fracture
Uneven
Transparency
Transparent to translucent
Crystal system
Tetragonal

Diagnostic features

## Identification Sweetite is identified by its characteristic crystal form – sharp, tetragonal dipyramids. Its occurrence in oxidized zones of zinc deposits, in association with minerals such as hydrozincite or calcite, is also an important diagnostic clue. The small size of the crystals often requires magnification for identification. ## Distinguishing from Similar Minerals It can be confused with other colorless secondary minerals. It differs from calcite by its lack of reaction with hydrochloric acid and a different crystal form. Compared to hydrozincite, sweetite forms more defined, sharp crystals and crystallizes in a different system. ## Crystal Forms Crystals are almost always simple, forming sharp, tetragonal dipyramids {101}. Additional faces are rarely observed. They occur as single, overgrown crystals on the surface of the host rock.

Geological environment

## Genesis Sweetite is a secondary mineral, forming in the oxidation (weathering) zones of zinc ore deposits. It forms at low temperatures as a result of surface water acting on primary minerals, such as sphalerite, in a carbonate-rich environment. ## Mineral Associations It most commonly co-occurs with calcite, hydrozincite, hemimorphite, smithsonite, as well as native lead and sphalerite. ## Localities The most important and type locality is the Milltown Quarry in Derbyshire, England. It is also known from the Tsumeb Mine in Namibia, the Kabwe Mine in Zambia, and several localities in Mexico (Ojuela Mine, Mapimí).

Rarity

Rare

For collectors

## Quality Criteria The most prized sweetite specimens are those with sharp, well-formed, transparent, and lustrous crystals that clearly contrast with the rock matrix. Due to their small size, the perfection of the crystal form is crucial. Specimens with more than one undamaged crystal are particularly sought after. ## Popular Localities Specimens from the type locality in Derbyshire, England, are the historical standard for this mineral. High-quality microcrystals also come from the Tsumeb Mine in Namibia, which is renowned for its exceptional secondary minerals.

Care and storage

## Cleaning Sweetite specimens should be cleaned with the utmost care, using a soft brush to remove dust. Due to its brittleness and potential reactivity, wet cleaning, especially with ultrasonics, is not recommended. ## What to Avoid Avoid contact with acids and other chemicals that can easily damage or dissolve the mineral. The crystals are brittle and susceptible to mechanical damage. Store away from heat sources. ## Storage It is recommended to store specimens in stable conditions, in enclosed "micromount" boxes that protect them from dust, shocks, and sudden changes in humidity. Avoid direct exposure to sunlight, although its effect on the mineral is not known.

External references

Sources

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