Anglesite
Chemical formula: Pb(SO₄)
Anglesite is a sulfate mineral, specifically lead sulfate, often forming crystals with a characteristic luster.
Description
## Characteristics Anglesite is a mineral belonging to the sulfate group, consisting of lead sulfate. It typically occurs as well-formed crystals, which can be isometric, tabular, or prismatic. Twinning is common. The surface of the crystals is often smooth and shiny. Anglesite specimens are distinguished by their significant specific gravity, which is typical for lead minerals. ## Physical Properties The hardness of anglesite on the Mohs scale is 2.5-3, making it a relatively soft mineral. It exhibits a luster ranging from adamantine to resinous, sometimes vitreous. It can be transparent, translucent, or opaque. The specific gravity of anglesite is 6.37 g/cm³. ## Colors and Varieties Anglesite is most commonly colorless or white. It can also exhibit shades of gray, yellow, green, or blue, often due to the presence of impurities or inclusions. It is colorless in transmitted light. ## History and Name The mineral was discovered in 1832. The name "anglesite" comes from the island of Anglesey in Wales, where it was first identified in the Parys Mine. ## Uses Anglesite is a lead mineral, which means it can be locally used as an ore of this metal. Due to its attractive crystals and luster, it is also valued by mineral collectors.
Diagnostic features
## Identification Anglesite can be identified by its characteristic, often adamantine luster, significant specific gravity, and relatively low hardness. It often occurs as well-formed crystals, which can be colorless, white, or slightly tinted. ## Distinguishing from Similar Minerals Anglesite is sometimes confused with cerussite, another lead mineral. However, cerussite has a higher hardness (3-3.5) and often forms crystals with more complex shapes. From barite, which is also a sulfate, anglesite is distinguished by its significantly higher density and the presence of lead in its chemical composition. ## Crystal Forms Anglesite forms isometric, tabular, prismatic crystals, as well as granular and massive aggregates. Twinning is common. Crystals can be well-formed, with distinct faces and sharp edges.
Geological environment
## Genesis Anglesite is a typical secondary mineral, forming in the oxidation zones of lead ore deposits. It forms as a result of the reaction of sulfate solutions with galena (lead sulfide) or other lead minerals. ## Mineral Associations Anglesite often co-occurs with other secondary lead minerals, such as cerussite, pyromorphite, mimetite, as well as with galena, limonite, barite, and quartz. ## Localities Known localities for anglesite include the island of Anglesey in Wales (Parys Mine), Tsumeb in Namibia, Broken Hill in Australia, Mexico (e.g., Mapimi), Morocco, and various locations in the United States (e.g., Arizona, Utah).
Rarity
Very Common
Collector aspects
## Quality Criteria The most valued anglesite specimens are those with well-formed, large, and transparent crystals with intense luster. Color purity (e.g., colorless, pale yellow, or blue) and the absence of mechanical damage also increase the specimen's value. Specimens with interesting mineral associations are also attractive. ## Popular Localities Specimens from Tsumeb in Namibia are particularly sought after, known for their large, often transparent crystals with beautiful colors. Specimens from Broken Hill in Australia and Mexico are also highly prized.
Care and storage
## Cleaning Anglesite is a relatively soft mineral, so it should be cleaned gently. A soft brush or paintbrush is sufficient for removing dust and light dirt. For heavier soiling, lukewarm distilled water can be used to gently rinse the specimen, avoiding prolonged soaking. ## What to Avoid Avoid using strong chemicals, acids, and bases, which can damage the mineral's surface. Anglesite is susceptible to impacts and scratches due to its low hardness. It should not be exposed to prolonged intense sunlight, which can affect its color, or to sudden temperature changes. ## Storage Anglesite specimens are best stored in closed display cases or boxes to protect them from dust and mechanical damage. Due to their softness, it is advisable to store them separately from harder minerals to prevent scratching. Stable temperature and moderate humidity are recommended for long-term preservation of specimens.