(1). Braunite: Mn2+Mn3+6[O8|SiO4]
Braunite is a silicate mineral, which contains both di- and tri-valent manganese. Common impurities include iron, calcium, boron, barium, titanium, aluminium, and magnesium.
Physical Properties of Braunite:
- Crystal System: Hexagonal
- Cleavage: Braunite has no cleavage
- Fracture: Uneaven
- Hardness: 6 – 6.5 on Moh’s scale
- Sp.Gr: 4.75 – 4.82
- Lustre: submetallic lustre
- Colour: brownish black to steel gray.
- Steak: Braunite give brownish gray to steel grey streak on grinding with streak plate.
- Habit: Massive and granular.
Braunite occurs in hydrothermal veins with other manganese oxides. It is also found with pyrolucite and psilomelane as secondary a mineral.
Uses of Braunite:
- Braunite is used as an ore of manganese.
- It is also used in steel making.
(2). Pyrolusite: MnO2
- Crystal System: Tetragonal
- Cleavage: perfect
- Hardness: 1-2 on Moh’s scale
- Specific Gravity: 4.75
- Lustre: Metallic to dull
- Colour: Iron black
- Streak: Iron Black
- Habit: As reniform sooty masses which soil the fingers. Rarely as elongated crystals.
Pyrolusite appears similar to psilomelane. It is a secondary mineral formed by the alteration of manganite or other primary manganese minerals. It is commonly found associated with braunite, goethite and limonite.
Uses of Pyrolusite:
- Pyrolusite is used in manufacturing steel.
- Pyrolusite is used as iron ore.
- It is also used to make manganese bronze.
- It is used in calico printing and dyeing.
(3). Psilomelane: (Ba•(H2O)Mn3+5O10)
- Crystal System: Orthorhombic
- Fracture: Uneven
- Hardness: 5-6 on Moh’s Scale
- Sp.Gr: 4.4 – 4.7
- Lustre: Submettalic lustre
- Colour: black
- Streak: Brownish Black, shining
- Habit: Massive, botryoidal and stalactitic
Psilomelane is a secondary mineral, which is formed by the weathering of manganese carbonates or silicates. it occurs usually with pyrolusite.
Uses of Psilomelane:
- It is used as an ore of manganese.
- Metaphysically it is important and used for gazing and scrying, and to bring good faith.
- As it contains Barium, therefore, it is considered as a good source of barium.
(4). Manganite: MnO (OH)
- Crystal System: monoclinic
- Cleavage: perfect
- Hardness: 4 on Moh’s scale
- Specific Gravity: 4.3
- Lustre: submetallic to dull
- Colour: steel gray to iron black.
- Streak: dark brown.
- Habit: prismatic crystals, often grouped in bundles. Also columnar.
Manganite is a low-temperature mineral found in hydrothermal veins. it is often associated with pyrolusite, geothite, and baryte.
Uses of Manganite:
- Used as a minor ore of manganese metal.
- In prehistoric times, its pigments were used as an igniter to burn wood fires.
- Minerals of Amphibole Group
- Minerals of Mica Group
- Minerals of Olivine Group
- Minerals of Garnet Group
- Minerals of Chlorite Group
- Minerals of Clay Group
- Minerals of Serpentine Group
- Polymorphs/ Minerals of Al2SiO5
- Calcium Minerlas
- Aluminium Minerals
- Iron Minerals