Barylite

Chemical formula: BaBe₂Si₂O₇

Barylite is a rare beryllium and barium silicate, prized by collectors for its well-formed, colorless or white crystals with a vitreous luster.

## Characteristics Barylite is a rare mineral from the silicate group, chemically classified as a beryllium and barium silicate. It typically forms tabular or prismatic crystals, often elongated. Specimens are most commonly colorless, white, or pale yellow, and exhibit a vitreous, sometimes slightly resinous luster. Crystals can occur as single, well-formed individuals or create radial and fan-shaped aggregates. Due to its rarity and attractive crystal forms, barylite is a sought-after collector's mineral. ## Physical Properties This mineral is characterized by a hardness of 6-7 on the Mohs scale, making it relatively scratch-resistant. Its crystals are usually transparent to translucent. The density of barylite is approximately 3.55 g/cm³, which is quite high for a silicate, resulting from the presence of heavy barium in its structure. It possesses perfect cleavage in two directions. ## Colors and Varieties Barylite is most often colorless or white. Rarer specimens exhibit a pale blue or pale yellow coloration. No named color varieties or commercial varieties are distinguished. ## History and Name The name barylite comes from the Greek words *βαρύς* (barýs) - "heavy" and *λίθος* (líthos) - "stone", which is a direct reference to its high density. The mineral was first described in 1876 by the Swedish mineralogist Christian Wilhelm Blomstrand based on specimens found in Långban, Sweden. ## Uses Barylite has no industrial applications. Its significance is limited to its role as a mineral of scientific and collectible value.

Properties

Mohs hardness: 6-7
Luster: Vitreous
Streak: White
Density: 3.5-3.6
Cleavage: Perfect on {001} and {110}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Barylite can be identified by its tabular or prismatic crystal habit, high density (the specimen feels surprisingly heavy for its size), vitreous luster, and perfect cleavage in two directions. Its characteristic fluorescence under shortwave UV light, where it glows blue or white-blue, is also distinctive. ## Distinguishing from Similar Minerals Barylite is sometimes confused with celestine or barite, but it is significantly harder than both (barite and celestine have a hardness of 3-3.5). It is distinguished from quartz by its higher density and perfect cleavage (quartz has no cleavage). Density and hardness tests are crucial in distinguishing it from similarly appearing minerals. ## Crystal Forms Barylite crystals are typically flattened, tabular, often with outlines resembling a rectangle or hexagon. They also occur as elongated prisms. They frequently form fan-shaped, radial, or granular aggregates.

Geological environment

## Genesis Barylite is a hydrothermal mineral. It forms in veins cutting zinc ore deposits, in skarns, and in some alkaline rocks, such as nepheline syenites. It is a product of crystallization from solutions rich in barium and beryllium. ## Mineral Associations This mineral often co-occurs with other beryllium and barium-bearing minerals. Its typical associations include: barite, calcite, quartz, franklinite, willemite, rhodochrosite, as well as rarer minerals such as edingtonite, harmotome, nasonite, and gillespite. ## Localities The most important and historical locality for barylite is Långban in Värmland, Sweden. Excellent specimens also come from the Franklin deposit in New Jersey, USA, where it occurred in association with franklinite and willemite. Other known localities include Murmansk in Russia (Khibiny Massif), Mont Saint-Hilaire in Canada, Wessels Mine in South Africa, and several places in China (e.g., Daye zinc mine).

Rarity

Rare

For collectors

## Quality Criteria Specimens with well-formed, sharp, and undamaged crystals of high transparency are most valued by collectors. Large, single crystals or aesthetic crystal groups on a rock matrix command the highest prices. Specimens from classic, historical localities like Franklin or Långban are also desirable. Clarity (lack of inclusions) and an intense, vitreous luster also significantly increase a specimen's value. ## Popular Localities Specimens from Franklin, New Jersey (USA) and Långban (Sweden) are considered classics and are highly regarded by collectors. In recent years, interesting specimens from China have also appeared on the market, distinguished by their good crystal form.

Care and storage

## Cleaning Barylite specimens can be cleaned with a soft, dry brush to remove dust. For heavier soiling, distilled water and a mild detergent are permissible, followed by thorough rinsing and drying. Ultrasonic cleaners should be avoided, as they can damage crystals along cleavage planes. ## What to Avoid Protect barylite from contact with strong acids, especially hydrofluoric acid, which can damage it. The mineral is stable under normal conditions, but extreme temperature changes should be avoided. Despite its relatively high hardness, it is brittle and susceptible to mechanical damage, particularly along cleavage directions. ## Storage Specimens should be stored in separate boxes or on a soft surface to prevent scratches and impacts that could cause fractures. Due to its rarity and collectible value, storage in stable conditions, away from dust and moisture, is recommended.

Sources

IMA Mineral List (CNMNC)