Laurelite
Chemical formula: Pb<sup>2+</sup><sub>7</sub>F<sub>12</sub>Cl<sub>2</sub>
Laurelite is a very rare lead fluoride-chloride, forming small, colorless or pale yellow crystals with a strong, adamantine luster.
Description
## Characteristics Laurelite is a rare mineral from the halide group, chemically a complex lead fluoride-chloride. It occurs as small, thin to thick, tabular crystals with a square or octagonal outline. They are typically colorless, white, or have a pale yellow hue. A characteristic feature of laurelite is its strong, adamantine luster, giving it a vivid appearance despite its small size. ## Physical Properties This mineral is relatively soft, with a Mohs hardness of 2.5, meaning it can be scratched with a fingernail. It is also extremely dense (6.96 g/cm³), which is typical for lead minerals and noticeable even in small specimens. It possesses perfect cleavage in one direction, making it brittle and susceptible to damage. It is transparent to translucent. ## Colors and Varieties Laurelite does not form color varieties or commercial forms. Its color palette is limited to shades of colorless, white, and pale yellow. ## History and Name The mineral's name comes from its discovery locality – Laurel Canyon, where the Grand Reef mine is located in Graham County, Arizona (USA). It was described and recognized as a new mineral species in 1989 by W. W. Pinch and J. E. Taggart, Jr. ## Applications Due to its extreme rarity and small crystal size, laurelite has no industrial applications. It is solely an object of scientific and collector interest.
Diagnostic features
## Identification Key diagnostic features of laurelite include its tetragonal, tabular crystals, adamantine luster, high density, and occurrence in paragenesis with other rare secondary minerals from the Grand Reef mine. It is very soft and has perfect cleavage. ## Distinguishing from Similar Minerals Laurelite can be confused with other colorless or white secondary lead minerals, such as cerussite or anglesite. Cerussite crystallizes in the orthorhombic system and often forms reticulated aggregates. Anglesite also crystallizes in the orthorhombic system and has a slightly higher hardness (2.5-3). Definitive distinction requires advanced analytical methods, but crystal habit and paragenesis are strong indicators. ## Crystal Forms Laurelite forms thin to thick tabular crystals with a square or octagonal cross-section. They occur individually or as small, partially overlapping groups and rosettes.
Geological environment
## Genesis Laurelite is a secondary mineral, forming in the oxidation zone of hydrothermal lead ore deposits. It forms as a result of the alteration of primary lead sulfides in the presence of fluoride and chloride ions. ## Mineral Associations This mineral occurs in association with other secondary lead minerals. The most common associated minerals include anglesite, cerussite, diaboleite, galena, linarite, and also rarer ones such as scrutinyite. ## Localities Laurelite is an extremely rare mineral. Its type locality and main occurrence is the Grand Reef mine in Laurel Canyon, Graham County, Arizona, USA. This is the only place in the world where specimens of collector significance have been obtained.
Rarity
Very rare
Collector aspects
## Quality Criteria The most highly prized laurelite specimens are those with sharply terminated, transparent, and well-formed crystals, set on a contrasting rock matrix. Association with other rare minerals from this locality, especially blue diaboleite, is also of great importance. Crystal size is a key factor, as most are only a few millimeters in diameter. ## Popular Localities The only source of valuable collector specimens of laurelite is its type locality – the Grand Reef mine in Arizona, USA. Specimens from this location are considered classics and are highly sought after by specialized collectors.
Care and storage
## Cleaning Laurelite is very soft and brittle, requiring extreme caution. Only a soft brush should be used to remove dust. If necessary, the specimen can be very gently rinsed in distilled water and then immediately dried. Ultrasonic cleaners or strong water jets should never be used. ## What to Avoid Avoid contact with acids and other chemicals. The mineral is sensitive to impact and scratching due to its low hardness and perfect cleavage. As a lead mineral, it is toxic – hands should be washed after any contact with the specimen. ## Storage Laurelite specimens are best stored in separate, padded membrane boxes or containers with soft inserts to protect them from mechanical damage and contact with harder minerals. It should be protected from dust and sudden temperature changes.