Nitrobarite
Chemical formula: Ba(N<sup>5+</sup>O<sub>3</sub>)<sub>2</sub>
Nitrobarite is a rare, water-soluble barium nitrate, forming colorless or white crystals in the isometric system.
Properties
- Mohs hardness
- 3
- Luster
- Vitreous
- Streak
- White
- Density
- 3.24
- Cleavage
- Perfect on {111}
- Fracture
- Conchoidal
- Transparency
- Transparent to Translucent
- Crystal system
- Cubic
Diagnostic features
## Identification A key diagnostic feature of nitrobarite is its very high solubility in water – a small fragment will dissolve in a drop of water. In the field, it can be recognized by its regular crystal form (if visible), relatively high density for a salt mineral, and softness. It occurs in specific, dry environments, such as caves or old mines in desert climates. ## Distinguishing from Similar Minerals Nitrobarite can be confused with other soluble nitrates, such as nitratine (sodium nitrate) or nitrocalcite (hydrated calcium nitrate). Nitratine crystallizes in the trigonal system, and nitrocalcite in the monoclinic system. It is distinguished from halite (rock salt) by the absence of a salty taste and higher density. A flame test can be helpful – barium colors the flame a characteristic pale green. ## Crystal Forms Nitrobarite crystallizes in the isometric system, most often forming crystals in the shape of cubes or octahedra, as well as their combinations. It is often found as granular aggregates and crystalline crusts on rocks.
Geological environment
## Genesis Nitrobarite is a secondary mineral, forming under extremely dry, desert climate conditions. It forms as a product of the reaction of nitrate-rich solutions with barium-bearing rocks. The source of nitrates is most often decaying organic matter, such as bat or bird guano. It forms as efflorescences and crusts on cave walls, in rock fissures, and in old, dry mine workings. ## Mineral Associations This mineral co-occurs with other nitrates and sulfates formed under similar conditions, such as nitratine, nitrocalcite, gypsum, and other rare, soluble salts. ## Localities The most important and classic locality for nitrobarite is the Santa Ana mine near Taltal, in the Antofagasta region of Chile – this is its type locality. It is also known from several locations in the United States, including the Tooele area in Utah.
Rarity
Very rare
For collectors
## Quality Criteria The collector's appeal of nitrobarite is inextricably linked to its rarity. Specimens with well-formed, sharp, and transparent crystals, embedded in a stable rock matrix, are most highly valued. Crystal size is a key factor – even millimeter-sized but well-formed cubes or octahedra are considered valuable. Due to the mineral's instability, the condition of the specimen is also important. ## Popular Localities By far the most sought-after specimens by collectors come from the type locality in Chile (Taltal), from where the world's best crystals of this mineral are known.
Care and storage
## Cleaning Nitrobarite is highly soluble in water, so under no circumstances should it be cleaned wet. To remove dust, use only a soft, dry brush or a very gentle stream of compressed air. ## What to Avoid Contact with water and all liquids must be strictly avoided. The mineral is also hygroscopic, meaning it absorbs moisture from the air, so it must be protected from humid environments. Abrupt temperature changes are also inadvisable. ## Storage Nitrobarite specimens require special storage conditions. They should ideally be kept in a sealed, airtight container (e.g., a "membrane box" or a closed display case) along with a desiccant (e.g., silica gel). Exposure to open air should be avoided.