Bromellite

Chemical formula: BeO

Bromellite is a rare beryllium oxide, most often forming small, hexagonal crystals with high hardness and a vitreous luster.

## Characteristics Bromellite is beryllium oxide (BeO), a mineral known for its chemical simplicity and exceptional physical properties. It typically occurs as small, well-formed crystals with a hexagonal prismatic or tabular habit, often terminated by pyramids. Specimens rarely exceed a few millimeters in size. Crystals can be transparent to translucent, with a strong, vitreous luster. Due to its rarity and small size, bromellite is primarily a mineral of scientific and collector interest. ## Physical Properties This mineral is characterized by very high hardness, measuring 9 on the Mohs scale, which places it among the hardest minerals, just behind diamond and corundum. Its density is relatively low for such a hard material, at about 3.01-3.02 g/cm³. Bromellite also exhibits a very high melting point, exceeding 2500 °C. Some specimens may show fluorescence under ultraviolet light, most often in shades of ivory or creamy white. ## Colors and Varieties Bromellite is most often colorless or white. It can also take on grayish, yellowish, or greenish hues, which is associated with the presence of trace impurities. No named color varieties or commercial varieties are distinguished. ## History and Name The mineral was first described in 1925 by the Swedish mineralogist Greg Aminoff. The name "bromellite" was given in honor of Magnus von Bromell (1679–1731), a Swedish physician and mineralogist who was one of the first to describe the phenomenon of fluorescence. The type locality, from which the first described specimens originated, is the Långban mine in the Värmland region of Sweden.

Properties

Mohs hardness: 9
Color: White to creamy white
Luster: Vitreous
Streak: White
Density: 3.017
Cleavage: on <mi>{10_10}</mi>
Fracture: Conchoidal to Uneven
Transparency: Transparent
Crystal system: Hexagonal

Diagnostic features

## Identification The key diagnostic feature of bromellite is its extreme hardness (9 on the Mohs scale), which can only be tested with corundum or diamond. Other helpful identification features include its hexagonal crystal form, vitreous luster, relatively low density for such a hard mineral, and often occurring fluorescence in shades of white or ivory under UV light. ## Distinguishing from Similar Minerals Bromellite is sometimes confused with phenakite, which is also a beryllium silicate and forms similar crystals, but has lower hardness (7.5-8). It can also be confused with colorless corundum, which has identical hardness but is significantly denser (approx. 4 g/cm³). From quartz, it is distinguished by its decidedly higher hardness. ## Crystal Forms Bromellite crystallizes in the hexagonal system, forming columnar or tabular crystals. They often occur as simple, six-sided prisms, frequently terminated by flat basal faces (pinacoid) or pyramidal faces. It is also found in the form of granular aggregates within other minerals.

Geological environment

## Genesis Bromellite is a hydrothermal or metamorphic mineral, forming in environments rich in beryllium and poor in silica. Its formation is only possible when silicon concentration is too low for more common beryllium silicates, such as beryl or phenakite, to form. It forms in skarns, calcite veins, and some pegmatites. ## Mineral Associations This mineral co-occurs with other beryllium minerals, such as phenakite, beryl, chrysoberyl, as well as with magnetite, hematite, calcite, hausmannite, tephroite, and swedenborgite, especially in manganese deposits like Långban and Franklin. ## Localities The most important and classic localities for bromellite are the Långban mine in Sweden and the Franklin and Sterling Hill deposits in New Jersey, USA. It is also known from several locations in Russia, including the Kola Peninsula and the Urals (Chelyabinsk region). A few occurrences have also been reported in the Green River Formation in Utah, USA.

Rarity

Very rare

For collectors

## Quality Criteria The most prized specimens by collectors are those with well-formed, sharp, and transparent crystals, especially those set on a contrasting rock matrix. Crystals with unusual coloration (e.g., greenish) or exhibiting strong fluorescence are also highly valued. Due to the general rarity of the mineral, even microscopic but well-formed crystals have significant collector value. ## Popular Localities Classic specimens, considered the best in the world, come from the historic localities of Långban (Sweden) and Franklin (New Jersey, USA). However, these are extremely difficult to acquire on the modern market. Specimens from Russian localities appear sporadically and are also highly valued.

Care and storage

## Cleaning Bromellite specimens are very hard and chemically resistant, which facilitates their cleaning. They can be washed in warm soapy water using a soft brush. Ultrasonic cleaning is also permissible, although caution should be exercised with specimens on a delicate rock matrix. ## What to Avoid Bromellite is resistant to most chemicals and temperature changes. However, it should be remembered that beryllium dust, which could be generated during mechanical processing (grinding, cutting), is highly toxic and carcinogenic if inhaled. Any dust-generating activities should be avoided without appropriate personal protective equipment. ## Storage Due to its high hardness, bromellite can scratch almost any other mineral (except diamond and corundum). It is recommended to store it in a separate display box or in a way that prevents contact with other, softer specimens in the collection.