Olivenite

Olivenite

Olivenite is a mineral known for its rich green color, a characteristic it owes to its copper arsenate composition. Its chemical formula is represented as Cu₂AsO₄OH, indicating that it consists of copper, arsenic, oxygen, and hydrogen. Olivenite belongs to the adamite group of minerals, which are arsenates with a general formula of A₂ZO₄OH, where A can be lead, zinc, copper, etc., and Z can be arsenate or phosphate.

Properties and Occurrence

Olivenite crystallizes in the monoclinic crystal system, displaying prismatic, acicular, or fibrous crystal habits. Its color ranges from dark green to olive green, and less commonly, brown or yellow. The mineral has a Mohs hardness of about 3 to 4, making it relatively soft and suitable for collection rather than practical use. It exhibits a vitreous to pearly luster and leaves a greenish streak when rubbed against a white porcelain plate.

Olivenite is often found in the oxidized zones of copper deposits, where it forms through the alteration of primary copper minerals. It is associated with other secondary minerals such as azurite, malachite, and limonite. Significant deposits of olivenite have been discovered in Cornwall, England; Tsumeb, Namibia; and in various locations in the United States, including Arizona and Nevada.

Uses and Significance

While olivenite is not mined for commercial purposes due to its rarity and the presence of arsenic, which poses handling and environmental concerns, it is highly valued by mineral collectors. Its striking green color and crystal forms make it a desirable addition to mineral collections. Additionally, the study of olivenite and related minerals can provide insights into the geochemical processes that occur in the oxidation zones of copper deposits.

Environmental and Health Concerns

Due to its arsenic content, care should be taken when handling olivenite specimens. Arsenic is a toxic element, and prolonged exposure can lead to health issues. It is recommended to wash hands after handling the mineral and to avoid inhaling any dust generated from it.

See Also

• Copper minerals
• Arsenate minerals
• Adamite
• Mineral collecting