Cesanite
Chemical formula: Ca<sub>2</sub>Na<sub>3</sub>(S<sup>6+</sup>O<sub>4</sub>)<sub>3</sub>OH
Cesanite is a rare calcium and sodium sulfate, forming tiny, colorless, acicular crystals in volcanic fumarole environments.
Properties
- Mohs hardness
- 3.5
- Luster
- Vitreous
- Streak
- White
- Density
- 2.91
- Cleavage
- Imperfect on {10-10}
- Fracture
- Conchoidal to uneven
- Transparency
- Transparent to Translucent
- Crystal system
- Hexagonal
Diagnostic features
## Identification A characteristic feature of cesanite is its occurrence environment – it is a product of high-temperature volcanic exhalations (fumaroles). Identification is based on observing the crystal form (hexagonal, acicular, or prismatic) and co-occurring minerals. Due to its small size, certain identification is almost exclusively possible using advanced analytical methods, such as X-ray diffraction (XRD). ## Distinguishing from Similar Minerals Cesanite can be confused with other colorless sulfates found in fumaroles, such as arcanite, thenardite, or aphthitalite. Visual distinction of these minerals in the form of fine crystals is practically impossible and requires specialized studies. ## Crystal Forms Cesanite crystals have a habit of slender, hexagonal prisms, often terminated by pyramids. They form acicular, fibrous, radial aggregates, as well as fine-grained coatings.
Geological environment
## Genesis Cesanite forms as a result of direct crystallization (sublimation) from hot volcanic gases in fumaroles. It is a typical mineral of exhalative environments, crystallizing at temperatures above 400°C. ## Mineral Associations This mineral often co-occurs with other products of volcanic sublimation, such as aphthitalite, arcanite, thenardite, and various halides. ## Localities The most important occurrences of cesanite worldwide include its type locality – the Cesano geothermal field in Lazio, Italy, as well as the fumaroles of Vesuvius (Italy) and Tolbachik volcano in Kamchatka (Russia).
Rarity
Very rare
For collectors
## Quality Criteria As a micromount mineral, the collector's value of cesanite depends on several factors. Specimens with well-formed, sharp, and transparent crystals are most prized. The abundance of crystals on the rock matrix and their size are also important, although they rarely exceed a few millimeters. Associations with other rare fumarolic minerals are also highly valued. ## Popular Localities Specimens from the fumaroles of Vesuvius and Tolbachik volcano are most widespread in collections. Material from the type locality (Cesano) is extremely rare and represents a great find for specialized collectors.
Care and storage
## Cleaning Cesanite is a water-soluble mineral, so it must absolutely not be cleaned with water. To remove dust, use a soft, dry brush or carefully blow off contaminants with compressed air from a safe distance. ## What to Avoid Avoid contact with water, all liquids, and chemicals. The mineral is sensitive to moisture, so it should be protected from high humidity. As a relatively soft and brittle mineral, it is susceptible to mechanical damage and scratches. ## Storage Cesanite specimens are best stored in a dry place, in sealed containers, such as micromineralogical display boxes or membrane boxes. This form of storage protects them from moisture, dust, and mechanical damage.