Edingtonite

Chemical formula: Ba(Si₃Al₂)O₁₀·₄H₂O

Edingtonite is a rare, white or colorless zeolite group mineral, forming characteristic short prismatic crystals.

## Characteristics Edingtonite is a hydrated barium aluminum silicate, belonging to the zeolite group. It forms well-developed, short prismatic or pseudo-tetragonal crystals, often with a square cross-section. It also occurs in fibrous, radial, or massive aggregates. Specimens are usually small, and individual crystals rarely exceed a few centimeters in length. It is valued by collectors for its classic, sharp crystal forms. ## Physical Properties Edingtonite crystals are characterized by a hardness of 4 on the Mohs scale. They have a vitreous luster, and sometimes a pearly luster on fracture surfaces. They are transparent to translucent. The mineral's density is approximately 2.7-2.8 g/cm³, which is a relatively high value for a zeolite, due to its barium content. ## Colors and Varieties Edingtonite is most commonly colorless, white, or grayish. Rarer specimens exhibit a delicate pink or yellowish tint. There are no named varieties of this mineral. ## History and Name The mineral was named in 1825 in honor of the Scottish mineral collector, James Edington (1787-1844), in whose collection the first studied specimens were found. They were described by Wilhelm von Haidinger. The original locality from which they came was likely a quarry in Old Kilpatrick, Scotland. ## Uses Due to its rarity and small crystal size, edingtonite has no industrial applications. It is solely a mineral of scientific and collector's interest.

Properties

Mohs hardness: 4-5
Color: Colorless to white
Luster: Vitreous
Streak: White
Density: 2.694
Cleavage: m {110}
Fracture: Uneven
Transparency: Transparent,Translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Edingtonite can be identified by its characteristic short prismatic crystals, often with a square cross-section, and by its relatively high density for a zeolite. It exhibits perfect cleavage in two directions, which may be visible on damaged crystals. ## Distinguishing from Similar Minerals It can be confused with other zeolites, such as natrolite or scolecite, which, however, usually form acicular or slender crystals. From barite and celestine, with which it sometimes co-occurs, it is distinguished by lower hardness and different crystal form. From quartz, it is distinguished by significantly lower hardness. ## Crystal Forms It most often forms short, prismatic crystals, often terminated by flat or low-pyramidal faces. Crystals can be single or form small groups. It also occurs in fibrous, radial aggregates, and as masses filling small voids in rock.

Geological environment

## Genesis Edingtonite is a low-temperature hydrothermal mineral. It forms in gas vesicles and fissures in volcanic rocks, such as basalts and phonolites. It is also found in veins cutting carbonatites and in some manganese ore deposits, where it forms as a result of metasomatic processes. ## Mineral Associations It often co-occurs with other zeolite group minerals, such as analcime, natrolite, thomsonite, as well as with calcite, barite, harmotome, prehnite, and quartz. ## Localities The most famous edingtonite localities in the world include the Ice River mine in British Columbia (Canada), which yields large and well-formed crystals. It also occurs in the Böhlet quarry in Västergötland (Sweden), in Långban (Sweden), in Old Kilpatrick, Scotland (the historical type locality), and in the manganese ore mine in Hotazel (South Africa). In the Czech Republic, it is found in the vicinity of Těšín.

Rarity

Rare

For collectors

## Quality Criteria The most prized specimens by collectors are those with sharp, well-formed, transparent crystals that are free from damage. Groups of crystals aesthetically set on a rock matrix are also highly valued. Crystal size is a key factor – specimens with crystals exceeding one centimeter are already considered exceptional. Contrast with associated minerals, e.g., a dark matrix, enhances the specimen's attractiveness. ## Popular Localities Edingtonites from the Ice River mine in Canada are by far the most sought after in the collector's market, having set the standard for quality for this mineral. Classic, though usually smaller, specimens also come from Sweden (Böhlet, Långban) and the Republic of South Africa (Hotazel).

Care and storage

## Cleaning Edingtonite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. Always allow the specimen to dry completely at room temperature. ## What to Avoid As a zeolite, edingtonite is sensitive to high temperatures, which can cause the loss of water from its structure and permanent damage. Contact with acids and other aggressive chemicals should be avoided. It should not be cleaned in ultrasonic cleaners. ## Storage Specimens should be stored in stable conditions, away from direct sunlight and heat sources. Due to its relatively low hardness, it should be protected from scratching by harder minerals. It is best stored in a separate box or on a soft base.