Sweetite
Sweetite is a rare hydrated borate mineral with the chemical formula CaB10O16(OH)6•5H2O. It crystallizes in the tetragonal system, typically forming as white to colorless, acicular (needle-like) crystals or fibrous aggregates. It often occurs as coatings or encrustations.
Occurrence and Formation:
Sweetite is a secondary mineral, meaning it forms through alteration or weathering processes of pre-existing borate minerals in arid or semi-arid environments. It is found in borate deposits associated with evaporite sequences, typically in sedimentary rocks. Some notable locations where sweetite has been identified include California (USA), Russia, and Kazakhstan.
Physical Properties:
- Color: White, Colorless, Transparent
- Luster: Silky, Vitreous
- Crystal System: Tetragonal
- Cleavage: Perfect on {001}
- Fracture: Uneven
- Hardness: 3-4 (Mohs scale)
- Density: 2.42 g/cm³
- Streak: White
- Optical Properties: Biaxial (+)
Distinguishing Characteristics:
Sweetite can be distinguished from other similar borate minerals by its crystal habit (acicular), perfect cleavage, and associated mineralogy. X-ray diffraction analysis is often required for definitive identification.
Uses:
Due to its rarity, sweetite does not have significant industrial applications. It is primarily of interest to mineral collectors and researchers studying borate mineralogy and the conditions of their formation.