Stringhamite
Chemical formula: CaCu²⁺SiO₄·H₂O
Stringhamite is a rare hydrated copper and calcium silicate, distinguished by its intense azure-blue color and occurrence in small, radial aggregates.
Properties
- Mohs hardness
- 3.5
- Luster
- Vitreous
- Streak
- Light blue
- Density
- 3.16
- Cleavage
- Good on {010}
- Fracture
- Uneven
- Transparency
- Transparent,Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Stringhamite can be identified by its characteristic azure-blue color and typical occurrence in the form of small, radial or spherical aggregates of acicular crystals. Field identification is practically impossible without appropriate equipment; it requires laboratory analysis. ## Distinguishing from Similar Minerals It can be confused with other blue secondary copper minerals, such as cyanotrichite, which forms similar acicular aggregates but has a lighter, sky-blue hue. Distinguishing it from other rare copper silicates, such as kinoite or apachite, requires advanced analytical methods, e.g., X-ray diffraction (XRD). ## Crystal Forms Crystals are very small, acicular or bladed, elongated along the b-axis. They most often form radial, stellate, or spherical aggregates on the surface of the host rock.
Geological environment
## Genesis Stringhamite is a secondary mineral, formed in the oxidation zones of copper deposits. It forms as a result of hydrothermal solutions acting on rocks rich in copper and calcium. In the type locality (Bawana Mine), it occurs in veins and fractures within tactites (contact-metasomatic rocks) formed at the contact of monzonite with limestones. ## Mineral Associations This mineral co-occurs with other minerals of the oxidation zone. In the type locality, it was found in association with thaumasite, kinoite, apachite, willemite, shattuckite, chrysocolla, bornite, chalcopyrite, and tenorite. ## Localities The most important and type locality for stringhamite is the Bawana Mine in the Rocky District, Beaver County, Utah, USA. This is the only confirmed and well-documented locality for this mineral in the world.
Rarity
Very rare
For collectors
## Quality Criteria The collectible appeal of a stringhamite specimen depends on several factors. Highly valued are specimens showing well-formed, spherical or radial aggregates of intense, azure-blue color. Contrast with the rock matrix and the presence of associated minerals that form an aesthetic composition are also important. Due to the microscopic size of the crystals, specimens are primarily evaluated under magnification. ## Popular Localities The only source of collectible specimens is the type locality – the Bawana Mine in Utah, USA. All specimens available on the market come from this single location, making them particularly sought after by collectors specializing in minerals from specific localities and rare mineral species.
Care and storage
## Cleaning Stringhamite specimens should be cleaned with the utmost care, preferably using compressed air to remove dust. Due to its softness and fragility, mechanical contact, including cleaning with even a soft brush, is discouraged. If liquid is necessary, brief rinsing in distilled water is recommended, followed by immediate and thorough drying. ## What to Avoid Avoid contact with acids and other chemicals that can damage the mineral. Stringhamite is sensitive to high temperatures and prolonged exposure to moisture. It should not be cleaned in ultrasonic cleaners. ## Storage Stringhamite specimens, typically in the form of micromounts, should be stored under stable conditions, in closed, padded boxes (so-called "micromount boxes") to protect them from dust, mechanical damage, and sudden changes in humidity.