Brianyoungite

Chemical formula: Zn<sup>2+</sup><sub>3</sub>CO<sub>3</sub>(OH)<sub>4</sub>

Brittle, pearly zinc carbonate, forming delicate, spherical aggregates in the oxidation zones of zinc deposits.

## Characteristics Brianyoungite is a hydrated zinc carbonate, known for forming extremely delicate and aesthetic aggregates. It most often occurs as white or colorless spherical (spherulitic), reniform, or botryoidal masses. Individual spherules rarely exceed a few millimeters in diameter and consist of microscopic, platy crystals. The surface of the aggregates is characterized by a strong, pearly luster, which gives the specimens a distinctive, shiny appearance. ## Physical Properties This mineral is extremely soft and brittle, making it very susceptible to mechanical damage. Its hardness is too low to be reliably measured by standard methods. The luster is typically pearly on the aggregate surfaces and vitreous on individual microcrystals. It is translucent, and in very small fragments, it can be transparent. The calculated density is approximately 3.95 g/cm³, but due to the porous nature of the aggregates, it is difficult to measure in practice. ## Colors and Varieties Brianyoungite is usually snow-white or completely colorless. It does not form colored varieties, nor are any trade names known. ## History and Name The mineral was recognized by the IMA in 1991, and its description was published in 1993. The name honors Brian Young (b. 1947), a geologist with the British Geological Survey, in recognition of his contributions to the study of the mineralogy of the Northern Pennines in England, where this mineral was first found. The discovery was made at the Brownley Hill Mine in Cumbria. ## Applications Brianyoungite has no industrial applications. It is solely an object of interest for mineral collectors and scientists studying the weathering processes of ore deposits.

Properties

Luster
Pearly
Streak
White
Density
3.95
Cleavage
Perfect on {001}
Transparency
Transparent to Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Characteristic features of brianyoungite include its snow-white color, strong pearly luster, and typical occurrence in the form of small, spherical aggregates. Its extreme brittleness and softness are also key indicators. As a carbonate, it reacts vigorously with acids, but this test is destructive and should be avoided. Its occurrence in abandoned zinc and lead mine workings is a strong clue. ## Distinguishing from Similar Minerals Brianyoungite is sometimes confused with hydrozincite, which forms similar aggregates and occurs in the same environment. However, hydrozincite often exhibits strong blue fluorescence under ultraviolet (UV) light, which brianyoungite does not possess. Smithsonite, another zinc carbonate, is much harder (4-4.5 on the Mohs scale) and rarely forms such delicate, pearly aggregates. Gypsum can form similar white masses but has a different crystal structure and is less brittle. ## Crystal Forms Brianyoungite crystals are microscopic, in the form of thin plates or lamellae. They form radial structures that build spherical, hemispherical, or reniform aggregates, as well as delicate crusts and coatings.

Geological environment

## Genesis Brianyoungite is a secondary mineral, forming in the oxidation (weathering) zones of zinc and lead ore deposits. Characteristically, it is a typical "post-mining" formation mineral, meaning it crystallizes contemporaneously, after mining operations have ceased. It forms as a result of the reaction of sulfate- and carbonate-rich waters with zinc minerals, such as sphalerite, in the humid environment of old adits, shafts, and mine dumps. ## Mineral Associations This mineral often co-occurs with other secondary zinc and lead minerals. Its most common associates are hydrozincite, smithsonite, cerussite, hemimorphite, as well as gypsum and sphalerite (as a primary mineral). ## Localities The most important and classic locality, and also the type locality, is the Brownley Hill Mine in Nenthead (Cumbria, England). Other known occurrences include mines in Wanlockhead, Scotland, Blanchard Mine in New Mexico (USA), and isolated occurrences in Germany and Austria.

Rarity

Rare

For collectors

## Quality Criteria The most highly prized brianyoungite specimens are characterized by abundant coverage of the rock matrix by well-formed, spherical aggregates with an intense pearly luster. The absence of damage is important – due to the extreme brittleness of the mineral, even the slightest touch can destroy the delicate spherules. A contrasting rock matrix and association with other rare secondary minerals also increase the value of the specimen. ## Popular Localities Specimens from the type locality – Brownley Hill Mine in England – are by far the most sought after by collectors. They are considered the global standard for this mineral. Specimens from the Blanchard Mine in the USA are also valued, often forming attractive compositions with other minerals.

Care and storage

## Cleaning Brianyoungite specimens are extremely delicate and sensitive to water. The only safe method for removing dust is to very carefully blow it off using a photographic air blower or a stream of compressed air from a distance. Brushes, paintbrushes, or any mechanical tools should never be used. ## What to Avoid Contact with water and all chemicals that could dissolve or damage the fragile crystals must be strictly avoided. The mineral is very sensitive to shocks, touch, and changes in humidity. Ultrasonic cleaners must not be used. ## Storage It is recommended to store specimens in tightly sealed "micromount" boxes, which protect them from dust, mechanical damage, and sudden changes in humidity. Avoid displaying them on open shelves, where the mineral could easily be damaged.

External references

Sources

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