Edwindavisite
Chemical formula: Cu<sup>2+</sup>((C<sub>2</sub>)<sup>6+</sup>O<sub>4</sub>)(N<sup>3-</sup>H<sub>3</sub>)
Edwindavisite is an extremely rare mineral, a hydrated copper oxalate with ammonia, discovered in Arizona.
Properties
- Mohs hardness
- 2
- Luster
- Vitreous
- Streak
- Light blue
- Density
- 2.42
- Cleavage
- Perfect on {100}
- Fracture
- Splintery
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Identification of edwindavisite is possible almost exclusively using advanced analytical methods, such as Raman spectroscopy or X-ray diffraction (XRD), due to its microscopic size and rarity. In collecting conditions, identification relies on its intensely blue color, acicular crystal habit, and, most importantly, a reliable label with the type locality. ## Differentiation from Similar Minerals It can be confused with other secondary, blue copper minerals with an acicular habit, such as chalcanthite, linarite, or cyanotrichite. "Eyeball" differentiation is practically impossible. Edwindavisite is distinguished by its unique chemical composition (copper oxalate with ammonia) and its genesis associated with bat guano. ## Crystal Forms It forms very fine, acicular or bladed crystals, which often arrange into radial or rosette-like aggregates. Crystals are elongated along the [001] axis.
Geological environment
## Genesis Edwindavisite is a secondary mineral, forming under specific conditions in a cave environment. Its formation is the result of the reaction of copper-rich solutions from the weathering of copper sulfides (such as chalcopyrite) with ammonia and oxalic acid, which are products of bat guano decomposition. It forms in a dry climate, which prevents its dissolution. ## Mineral Associations At the type locality, it co-occurs with other rare oxalate minerals, such as moolooite, wheatleyite, and tinnunculite, as well as with gypsum, jarosite, and sulfur. ## Localities The only known occurrence (type locality) of edwindavisite is the Rowley Mine in Maricopa County, Arizona, USA.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of an edwindavisite specimen primarily depends on the richness and aesthetics of the aggregates on the matrix. The most valued specimens are those with distinct, well-formed, radial groupings of an intensely blue color, contrasting with the substrate. Due to the microscopic nature of the mineral, the ability to take high-quality photomicrographs is crucial. ## Popular Localities The only source of specimens is the Rowley Mine in Arizona. Material from this locality is the absolute standard and the only one available on the collector's market.
Care and storage
## Cleaning Due to its extreme delicacy and reactivity, edwindavisite specimens should not be wet cleaned. The safest method is to remove dust using a photographic blower or a stream of compressed air from a distance. ## What to Avoid Contact with water, acids, bases, and all chemical solvents, which can immediately dissolve or damage the mineral, must be absolutely avoided. The mineral is unstable in contact with water. It should be protected from high temperatures and humidity. ## Storage Specimens should be stored in a dry, stable environment, preferably in a tightly sealed "perky box" or a membrane capsule, to protect them from moisture, dust, and mechanical damage.