Manganese Minerals

(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.

Occurrence: 

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

Physical Properties:

• 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. 

Occurrence:

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)

Physical Properties:

• 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

Occurrence:

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)

Physical Properties:

• 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.

Occurrence:

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.

Read also:

1. Minerals of Amphibole Group
2. Minerals of Mica Group
3. Minerals of Olivine Group
4. Minerals of Garnet Group
5. Minerals of Chlorite Group
6. Minerals of Clay Group
7. Minerals of Serpentine Group
8. Polymorphs/ Minerals of Al₂SiO₅
9. Calcium Minerlas
10. Aluminium Minerals
11. Iron Minerals