Loseyite

Properties

Mohs hardness

3

Color

White to colorless, may be tannish- brown due to staining; colourless in transmitted light. Examination of the type specimen at Harvard University suggests that the color of loseyite can vary when in daylight to "daylight LED" to fluorescent white light.

Luster

Pearly

Streak

white

Density

3.27

Cleavage

Perfect on {010}

Fracture

Irregular/Uneven

Transparency

Transparent,Translucent

Crystal system

Monoclinic

Diagnostic features

## Identification Loseyite is difficult to identify visually without knowledge of the geological context. Key features include its occurrence in association with minerals from Franklin, very small, bladed, colorless crystals with a pearly luster, and extreme softness. It effervesces in hydrochloric acid. ## Differentiation from Similar Minerals It can be confused with other secondary, colorless zinc and manganese minerals from Franklin, such as hydrozincite or rosasite (in its rare, colorless forms). Hydrozincite often forms coatings and crusts, rather than distinct bladed crystals. Final differentiation from similar, rare minerals often requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms It forms elongated, bladed or thin-tabular crystals, often flattened. They typically occur as radial or haphazardly arranged aggregates on the surface of other minerals, mainly calcite.

Geological environment

## Genesis Loseyite is a secondary mineral, formed as a result of hydrothermal alteration of primary zinc and manganese ores in the Franklin deposit in New Jersey. It forms in fractures and voids within massive ores, mainly in calcite, in the oxidation zone. ## Mineral Associations It most commonly co-occurs with calcite, pyrochroite, sussexite, franklinite, and zincite. Its presence is closely linked to the unique geological environment of the Franklin deposit. ## Localities The only confirmed and well-documented locality for loseyite in the world is its type locality - the Franklin Mine in Sussex County, New Jersey, USA. It is an endemic mineral to this deposit.

Rarity

Very rare

For collectors

## Quality Criteria The collectible appeal of a loseyite specimen primarily depends on the size and development of the crystals and the richness of the aggregate. Since the crystals are always small, even millimeter-sized, well-formed blades are highly prized. The aesthetic composition with associated minerals is also important, especially the contrast with colorful calcite. Specimens with distinct, undamaged, radial aggregates are the most sought after. ## Popular Localities The only source of loseyite specimens is the historic Franklin Mine in New Jersey, USA. All specimens available on the collector's market come from this single location, making them particularly valuable for specialists collecting minerals from this locality.

Care and storage

## Cleaning Loseyite specimens are extremely delicate and sensitive to chemicals. Cleaning should be kept to an absolute minimum. If necessary, a very soft brush can be used to dry-dust. Avoid water and any chemicals. ## What to Avoid Loseyite is a carbonate, so it reacts with acids, even weak ones. Avoid contact with all chemicals, including water, which may contain dissolved gases forming weak acids. The crystals are very soft and brittle, so avoid any shocks, pressure, or attempts to scratch them. Do not clean it with ultrasonics. ## Storage Specimens should be stored in stable conditions, away from dust, moisture, and sources of vibration. The best solution is a sealed "micromount" box or a display case that protects delicate crystals from mechanical damage and contamination.

External references

• https://www.mindat.org/min-2438.html

Sources

• Mindat - Loseyite
• IMA Mineral List (CNMNC)