Raydemarkite
Chemical formula: Mo⁶⁺O₃·H₂O
Raydemarkite is a hydrated molybdenum oxide, forming microscopic, colorless to white crystals with a bladed or acicular habit.
Properties
- Mohs hardness
- 1.5-0
- Color
- Colorless
- Luster
- Vitreous to Pearly
- Streak
- White
- Density
- 3.44
- Cleavage
- {100} and {001}.
- Fracture
- Micaceous
- Transparency
- Transparent
- Crystal system
- Triclinic
Diagnostic features
## Identification Field identification of raydemarkite is practically impossible without specialized equipment. In a collection, it is identified based on its characteristic appearance – fine, bladed or acicular crystals with a pearly luster, gathered in small aggregates. Association with the locality (uranium-molybdenum mines) and accompanying minerals is key. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD) or Raman spectroscopy. ## Distinguishing from similar minerals Raydemarkite can be confused with other secondary molybdates, such as molybdite (MoO₃) or szenicsite (MoO₃·0.5H₂O). Molybdite is anhydrous and crystallizes in the orthorhombic system, while raydemarkite is monoclinic and hydrated. Szenicsite has a different water content. Visually, it may also resemble gypsum, but it occurs in a completely different geological environment. Certain differentiation is only possible through laboratory analysis. ## Crystal forms Crystals are elongated and flattened, forming bladed or acicular shapes. They often occur as radial or tangled aggregates, as well as coatings and efflorescences on the host rock.
Geological environment
## Genesis Raydemarkite is a secondary mineral, forming in the oxidation zones of molybdenum deposits, often in association with uranium deposits. It forms as a result of weathering and oxidation of primary molybdenum sulfides, such as molybdenite, under low-temperature conditions and the presence of water. ## Mineral associations At the type locality (Freedom No. 2 mine), raydemarkite co-occurs with jordisite, calcite, quartz, gypsum, uraninite, as well as other secondary molybdates like szenicsite and calcurmolite. ## Localities The only confirmed and described locality for raydemarkite in the world is its type locality: the Freedom No. 2 uranium mine, Red Canyon District, San Juan County, New Mexico, USA.
Rarity
Extremely rare
For collectors
## Quality criteria The quality of a raydemarkite specimen primarily depends on the richness and aesthetics of the crystal aggregates. Most valued are specimens with clearly visible, well-formed, though still microscopic, crystals forming visually attractive groups on a small fragment of the host rock. Color contrast with the matrix also enhances aesthetic value. Due to its microscopic nature, specimens are evaluated mainly under magnification. ## Popular localities The only source of raydemarkite specimens is its type locality in New Mexico, USA. All specimens available on the collector's market originate from this single mine.
Care and storage
## Cleaning Raydemarkite specimens are extremely delicate and brittle. Any mechanical cleaning, including the use of brushes, should be avoided. If cleaning is absolutely necessary, compressed air can be carefully used from a safe distance to remove loose dust. Contact with water may potentially alter its structure. ## What to avoid Contact with water, chemicals, ultrasound, and sudden temperature changes must be strictly avoided. The mineral is very soft and sensitive to any shocks and abrasions. It should not be exposed to direct sunlight. ## Storage Specimens should be stored under stable conditions, preferably in sealed, padded "micromount" boxes, to protect them from mechanical damage, dust, and moisture. Due to its brittleness, any manipulation of the specimen requires utmost caution.