Lautarite
Chemical formula: Ca(I<sup>5+</sup>O<sub>3</sub>)<sub>2</sub>
Lautarite is a rare calcium iodate, forming colorless or yellowish crystals with a vitreous luster, found in nitrate deposits in Chile.
Properties
- Mohs hardness
- 3.5-4
- Luster
- Vitreous
- Streak
- White
- Density
- 4.59
- Cleavage
- Good on {110}
- Fracture
- Conchoidal
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Lautarite is identified by its crystal habit (monoclinic, prismatic crystals), high density, vitreous luster, and characteristic occurrence environment in dry nitrate deposits (saltpeter). It is one of the few naturally occurring iodates. ## Distinguishing from Similar Minerals It can be confused with other minerals found in saltpeter deposits, such as nitronatrite or anhydrite. However, it is distinguished from them by its significantly higher density, characteristic crystal form, and lack of reaction with water (unlike nitronatrite, which is highly hygroscopic). From the similar iodate, brüggenite, it differs in its crystallographic system. ## Crystal Forms Lautarite crystals are monoclinic, usually prismatic in habit, often elongated along one axis. They can form radial aggregates or occur as single, overgrown crystals in druses.
Geological environment
## Genesis Lautarite is a secondary mineral. It forms in extremely dry, desert climatic conditions as a result of the oxidation of primary iodine-bearing minerals within nitrate deposits (Chilean saltpeter). ## Mineral Associations It most commonly co-occurs with other nitrate and sulfate minerals typical of Chilean saltpeter, such as nitronatrite, anhydrite, gypsum, halite, as well as other rare iodates like brüggenite and dietzeite. ## Localities The most important and classic occurrences of lautarite are found in Chile, in the Atacama Desert, in the Antofagasta (e.g., Lautaro mines, Oficina Pampa Blanca) and Tarapacá (e.g., Oficina Alianza) regions. These are the only confirmed localities where this mineral occurs in well-formed specimens.
Rarity
Rare
For collectors
## Quality Criteria The most prized specimens by collectors are those with sharply terminated, transparent, and well-formed crystals that contrast with the rock matrix. The absence of damage, cleanliness, and crystal size are important. Particularly sought after are groups of crystals forming visually attractive druses or radial aggregates. ## Popular Localities By far the most desirable specimens come from historical localities in Chile, such as the Lautaro mine or Oficina Pampa Blanca in the Antofagasta region. Specimens from these locations are considered classic and serve as a benchmark for the quality of this mineral.
Care and storage
## Cleaning Lautarite specimens should be cleaned with the utmost care. Due to its water solubility, absolutely avoid contact with water. For dust removal, a soft, dry brush or compressed air from a safe distance can be used. ## What to Avoid Avoid all contact with water, acids, and other chemicals that could damage or dissolve it. The mineral is relatively soft and brittle, so it must be protected from impacts, scratching, and vibrations. Store away from heat sources. ## Storage It is recommended to store specimens in a dry place, preferably in a sealed, closable display box, away from moisture. To prevent mechanical damage, each specimen should be isolated from other minerals.