Kutnohorite Mineral Overview

• Mineral name: Kutnohorite
• Mineral class: Carbonate (calcite group)
• Chemical formula: Ca(Mn²⁺,Mg,Fe)(CO₃)₂
• Crystal system: Trigonal
• Mohs hardness: 3.5–4
• Color range: Pink, pale pink, white, gray, brown
• Luster: Vitreous to pearly
• Streak: White
• Cleavage: Perfect (rhombohedral)
• Fracture: Uneven
• Specific gravity: Approximately 3.1–3.3
• Transparency: Transparent to translucent
• Common locations: Czech Republic, South Africa, Japan, Peru
• Uses: Collector mineral, ornamental stone
• Similar minerals: Dolomite, rhodochrosite, calcite

Naming and Classification

Kutnohorite is a manganese-bearing carbonate mineral, part of the dolomite group.

It is named after Kutná Hora in the Czech Republic, a historic mining region where it was first identified.

It forms a solid solution series with:

• Dolomite (CaMg(CO₃)₂)
• Ankerite (iron-rich variety)

The presence of manganese gives kutnohorite its distinctive color.

Physical and Optical Characteristics

Kutnohorite typically occurs as:

• Rhombohedral crystals
• Botryoidal (rounded) masses
• Banded or layered aggregates

Its color is often soft pink, but can vary:

• Pale pink to rose
• White or gray
• Brownish depending on iron content

The luster is vitreous, with a pearly sheen on cleavage surfaces.

With a Mohs hardness of 3.5–4, it is relatively soft.

Color (Key Feature)

The pink coloration of kutnohorite is due to:

• Manganese (Mn²⁺) in the structure

This gives it a visual similarity to rhodochrosite, though typically:

• Less intensely colored
• More subtle and pale

Chemical Composition and Structure

Kutnohorite is composed of:

• Calcium (Ca)
• Manganese (Mn), magnesium (Mg), and iron (Fe)
• Carbonate groups (CO₃)

It has a rhombohedral carbonate structure, similar to calcite and dolomite, allowing for:

• Extensive chemical substitution

Formation and Geological Occurrence

Kutnohorite forms in a variety of environments:

Hydrothermal Veins

• Associated with metal-rich mineralization

Sedimentary and Metamorphic Settings

• Replacement of earlier carbonate minerals

Typical formation conditions include:

• Presence of manganese-rich fluids
• Low to moderate temperatures

It is commonly associated with:

• Rhodochrosite
• Sphalerite
• Galena
• Quartz

Common Locations

Kutnohorite is found in several notable regions:

• Czech Republic: Kutná Hora (type locality)
• South Africa: Kalahari manganese field
• Japan: Manganese deposits
• Peru: Hydrothermal vein systems

South African specimens are especially well known.

Uses and Practical Significance

Kutnohorite has limited industrial use but is valued for:

Collector Mineral

• Attractive pink color
• Crystal and botryoidal forms

Ornamental Stone

• Occasionally used in carvings and decorative pieces

Similar and Related Minerals

Kutnohorite can resemble:

• Rhodochrosite: Typically deeper pink and more vivid
• Dolomite: Usually lacks pink coloration
• Calcite: Softer and reacts more strongly with acid

Chemical composition and color help distinguish it.

Identification Notes for Collectors

• Look for pale pink carbonate material
• Note rhombohedral cleavage
• Check moderate softness (3.5–4)
• Observe vitreous to pearly luster
• Consider association with manganese-rich deposits

Kutnohorite is a manganese-bearing carbonate mineral, recognized for its soft pink coloration and relationship to the dolomite group, making it a subtle but attractive mineral for collectors and a useful indicator of manganese-rich environments.