Nifontovite
Chemical formula: Ca<sub>3</sub>[BO(OH)<sub>2</sub>]<sub>6</sub>·2H<sub>2</sub>O
Nifontovite is a rare, colorless or white hydrated calcium borate, forming vitreous, tabular or prismatic crystals.
Properties
- Mohs hardness
- 3.5
- Luster
- Vitreous, Pearly on cleavage surfaces
- Streak
- White
- Density
- 2.28-2.31
- Cleavage
- Perfect on {010}
- Fracture
- Conchoidal
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Nifontovite can be identified by its characteristic crystal habit – short, prismatic or tabular. Key features include vitreous luster, low hardness (can be scratched with a knife), perfect cleavage in one direction, and occurrence in a specific geological environment (skarns). ## Distinguishing from similar minerals It can be confused with other colorless borates or skarn minerals, such as datolite, colemanite, or howlite. It differs from datolite by its lower hardness and different crystal form. Colemanite has similar hardness but also a different crystal habit and perfect cleavage. Howlite usually occurs in massive or reniform aggregates, rarely forming distinct crystals. ## Crystal forms Nifontovite crystals are usually short-prismatic, often flattened, with a tabular habit. They occur as single, well-formed individuals or form radial and granular aggregates.
Geological environment
## Genesis Nifontovite is a hydrothermal mineral, typical of magnesian-calcic skarns. It forms in the contact zone of magmatic intrusions (e.g., granitoids) with carbonate rocks (limestones, dolomites), under conditions of boron enrichment. ## Mineral associations It most often co-occurs with other borate minerals, such as kurchatovite, sibirskite, frolovite, as well as with calcite, dolomite, garnets (andradite, grossular), diopside, magnetite, and ludwigite. ## Localities The most important and classic locality for nifontovite is the Solongo boron deposit in Buryatia, Russia, where it was discovered. It is also known from several other localities worldwide, including the Fuka mine in Okayama Prefecture, Japan, and the Titovskoye deposit in Yakutia (Russia).
Rarity
Rare
For collectors
## Quality criteria The most valued specimens by collectors are those with well-formed, sharp, transparent, and colorless crystals. Large, single crystals or aesthetic crystal groups embedded in a contrasting rock matrix are also highly prized. Clarity (lack of inclusions) and undamaged crystal terminations significantly increase the value of a specimen. ## Popular localities By far the most desirable specimens come from the type locality – the Solongo deposit in Russia. Crystals from there are considered exemplary for this mineral. Specimens from the Fuka mine in Japan, although also valued, are usually smaller.
Care and storage
## Cleaning Nifontovite specimens should be cleaned very carefully, using a soft brush to remove dust. Due to its low hardness and perfect cleavage, ultrasonic cleaners and steam cleaning should be avoided. Brief rinsing in distilled water is permissible, followed by thorough drying. ## What to avoid Avoid contact with acids and other chemicals that may damage the mineral. Nifontovite is brittle, so it must be protected from impacts and scratches. It should not be heated or exposed to sudden temperature changes. ## Storage Specimens should be stored in separate, padded boxes or display cases to avoid contact with harder minerals. It is best to display it in stable conditions, away from direct sunlight and sources of moisture.