Boojumite

Chemical formula: Pb₂+₈O₄(OH)₂(S₆+O₃S₂-)₃

Boojumite is a very rare, secondary lead mineral, distinguished by its silky luster and occurrence in delicate, fibrous aggregates.

## Characteristics Boojumite is a very rare, complex lead sulfate-thiosulfate. It forms aggregates of fine, flexible fibers and needles, which can create mats or silky-looking masses. Individual crystals are too small to be seen with the naked eye. It is a secondary mineral, formed by the weathering of other lead minerals. ## Physical Properties Boojumite crystals are flexible. The mineral is characterized by a silky luster, and in the case of compact aggregates, a dull luster. It is opaque. ## Colors and Varieties Boojumite is usually white, but can also be colorless or pale yellow. No varieties have been distinguished. ## History and Name The mineral was discovered in the Kintore mine in the Broken Hill region of New South Wales, Australia. Its name comes from "Boojum," a fantastic creature from Lewis Carroll's poem "The Hunting of the Snark." This name refers to the fact that the mineral "vanished" (dissolved) upon contact with hydrochloric acid used to clean specimens, much like the Boojum from the poem, which suddenly disappeared. It was officially recognized by the IMA in 2017. ## Uses Due to its extreme rarity and small crystal size, boojumite has no practical applications. It is solely an object of interest for collectors of rare minerals and scientists.

Properties

Mohs hardness: 2
Luster: Silky
Streak: White
Density: 7.16
Cleavage: Perfect on {100}
Fracture: Fibrous
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Boojumite can be recognized by its unique form of occurrence – as white, silky, flexible fibers and needles forming tangled aggregates. Its occurrence in the oxidation zones of lead deposits is a key indicator. Final identification requires advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other secondary, fibrous lead minerals, such as hydrocerussite, anglesite, or cerussite in acicular form. However, boojumite is distinguished by the flexibility of its fibers and its characteristic reaction to hydrochloric acid (dissolution). Distinguishing it from visually identical "matlockite" (which is often a mixture of minerals in reality) is impossible without analysis. ## Crystal Forms This mineral forms elongated, acicular or hair-like crystals up to 1 mm long, which combine into tangled, fibrous or felt-like aggregates. Small, radial aggregates are less common.

Geological environment

## Genesis Boojumite is a secondary mineral that forms in the oxidation zones (gossans) of lead ore deposits. It is formed as a result of complex chemical reactions occurring during the weathering of galena and other sulfides in the presence of solutions rich in sulfates and other ions. ## Mineral Associations It most often co-occurs with other secondary lead minerals, such as anglesite, cerussite, lanarkite, leadhillite, susannite, as well as with quartz and goethite. Its presence is strongly associated with minerals from the lanarkite-susannite group. ## Localities The type and main locality, from which most known specimens originate, is the Kintore Open Cut mine in Broken Hill, New South Wales, Australia. It has also been identified in several other places worldwide, including mines in the Lavrion region of Greece, but these occurrences are of much lesser significance.

Rarity

Extremely rare

For collectors

## Quality Criteria The most prized boojumite specimens are those that show rich, dense, and pure white coatings with a clearly visible, silky fibrous structure. The contrast with the dark host rock (matrix) significantly enhances visual appeal. The size of the area covered by the mineral and the absence of damage to the delicate fibers are also important. ## Popular Localities The only significant locality from a collector's perspective is the historical type locality – the Kintore mine in Broken Hill, Australia. Specimens from this location are considered classic and most desirable.

Care and storage

## Cleaning Boojumite is extremely delicate and chemically sensitive. It should not be wet cleaned. Any contaminants should be removed only mechanically, dry, using a very soft brush or a low-pressure stream of compressed air. ## What to Avoid Absolutely avoid contact with water, acids (especially hydrochloric acid, in which it dissolves), and other chemicals. The mineral is sensitive to changes in humidity and temperature. Protect it from direct sunlight. ## Storage Boojumite specimens must be stored in dry conditions, preferably in a tightly sealed container (e.g., a "perky box") away from sources of moisture and at a stable temperature. Due to the fragility and delicacy of the fibers, avoid any vibrations and shocks.

Sources

IMA Mineral List (CNMNC)