Inderite
Chemical formula: Mg[B<sub>3</sub>O<sub>3</sub>(OH)<sub>5</sub>](H<sub>2</sub>O)<sub>4</sub>·H<sub>2</sub>O
Inderite is a hydrated magnesium borate, forming colorless or white, prismatic crystals, often in radial aggregates.
Properties
- Mohs hardness
- 2.5
- Luster
- Vitreous, Pearly
- Streak
- White
- Density
- 1.782
- Cleavage
- Perfect on {110}, good on {1-10}
- Fracture
- Conchoidal
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Inderite can be identified by its characteristic, prismatic crystals, often forming radial aggregates. Its low hardness (2.5 on the Mohs scale), low density, and vitreous or pearly luster are key features. An important clue is its instability in dry air, where it whitens and dulls. ## Distinguishing from Similar Minerals Inderite is sometimes confused with kurnakovite, which is a product of its dehydration and often forms pseudomorphs with it. Kurnakovite, however, has a slightly higher hardness (3 on the Mohs scale). It can also resemble other borates, such as colemanite or ulexite, but differs from them in crystal form and physical parameters. Ulexite is known for its "optical fiber" effect, which inderite does not exhibit. ## Crystal Forms Inderite crystals are typically elongated, prismatic, with a square or rectangular cross-section. They often occur as radial or stellate aggregates. Fibrous, matted, and granular masses are also found.
Geological environment
## Genesis Inderite is a sedimentary mineral. It forms as a result of evaporation of saline borate lake waters in dry and hot climatic conditions. It crystallizes directly from solutions rich in boron and magnesium. ## Mineral Associations This mineral often co-occurs with other borates, such as hydroboracite, kurnakovite (often as an alteration product), inyoite, colemanite, as well as with gypsum, anhydrite, and halite. ## Localities The most important and classic localities for inderite are in the Inder Lake region of Kazakhstan. Significant specimens also come from Boron in Kern County, California (USA), and from Bigadiç in Balıkesir Province, Turkey. Occurrences have also been reported in Argentina (e.g., at the Tincalayu mine in Salta Province).
Rarity
Not very common
For collectors
## Quality Criteria The most valued specimens by collectors are those with well-formed, transparent, prismatic crystals, forming visually attractive, radial aggregates. The size of the crystals, their luster, and the absence of damage are important. Specimens from classic localities, such as Kazakhstan or California, are particularly sought after. Due to the mineral's instability, its good state of preservation (absence of signs of dehydration) is also crucial. ## Popular Localities The best localities for this mineral are considered to be in Kazakhstan (Inder) and the USA (Boron, California), from which large and well-formed crystals originate. Specimens from Turkey (Bigadiç) are also valued in the collector's market.
Care and storage
## Cleaning Inderite specimens should be cleaned very carefully, only dry, using a soft brush to remove dust. Contact with water, especially warm water, can cause partial dissolution and damage to the mineral's surface. ## What to Avoid Contact with water and all chemicals must be absolutely avoided. Inderite is sensitive to changes in humidity – in dry air, it can dehydrate, losing its luster and becoming a white, powdery aggregate of kurnakovite. It should be protected from high temperatures and direct sunlight. ## Storage It is recommended to store inderite in airtight, sealed containers (e.g., "membrane box" type or in boxes with controlled humidity) to prevent its dehydration. It should be kept away from heat sources and in stable humidity conditions.