Humite Mineral Overview
- Mineral name: Humite
- Mineral class: Silicate (nesosilicate, humite group)
- Chemical formula: (Mg,Fe)₇(SiO₄)₃(F,OH)₂
- Crystal system: Orthorhombic
- Mohs hardness: 6–6.5
- Color range: Yellow, orange, brown, reddish
- Luster: Vitreous
- Streak: White
- Cleavage: Poor
- Fracture: Uneven to subconchoidal
- Specific gravity: Approximately 3.2–3.4
- Transparency: Transparent to translucent
- Common locations: Italy, Russia, United States, Norway
- Uses: Collector mineral, rare gemstone
- Similar minerals: Olivine, chondrodite, clinohumite
Naming and Classification
Humite is a magnesium-rich silicate mineral and the namesake of the humite group, which includes:
- Chondrodite
- Clinohumite
- Norbergite
It was named after Sir Abraham Hume, an English mineralogist and collector.
Physical and Optical Characteristics
Humite typically occurs as:
- Short prismatic or granular crystals
- Massive aggregates
Its color is usually warm-toned, including:
- Yellow
- Orange
- Brown
- Reddish hues
The luster is vitreous, giving it a glassy appearance.
With a Mohs hardness of 6–6.5, it is moderately hard.
Crystal Habit (Key Feature)
Humite crystals are often:
- Stubby, prismatic, or granular
They may resemble:
- Olivine crystals but typically show more variation in color
Chemical Composition and Structure
Humite is composed of:
- Magnesium (Mg) and iron (Fe)
- Silicon (Si)
- Oxygen (O)
- Fluorine (F) and hydroxyl (OH)
It has a nesosilicate structure, similar to olivine, but modified by:
- The presence of fluorine and hydroxyl
Formation and Geological Occurrence
Humite forms in metamorphosed carbonate rocks, particularly:
Contact Metamorphism
- Limestone or dolomite altered by nearby magma
Typical formation conditions include:
- High temperatures
- Magnesium-rich environments
- Presence of fluorine-bearing fluids
It is commonly associated with:
- Calcite
- Dolomite
- Spinel
- Forsterite
Common Locations
Humite is found in several classic localities:
- Italy: Vesuvius region (type locality)
- Russia: Ural Mountains
- United States: New Jersey, New York
- Norway: Metamorphic deposits
Italian specimens are especially well known.
Uses and Practical Significance
Humite has limited practical use:
Collector Mineral
- Attractive color and rarity
- Interest within the humite group
Gemstone Use
- Occasionally faceted
- Rare due to limited availability
Similar and Related Minerals
Humite can resemble:
- Olivine: More common and typically greener
- Chondrodite: Closely related but more common
- Clinohumite: Similar but monoclinic
Careful identification may require crystallographic or chemical analysis.
Identification Notes for Collectors
- Look for yellow to brown prismatic or granular crystals
- Note moderate hardness (6–6.5)
- Observe vitreous luster
- Check association with metamorphosed carbonate rocks
- Consider presence of fluorine-bearing minerals
Humite is a magnesium-rich nesosilicate mineral, recognized for its association with metamorphosed carbonate rocks and its role within the humite group, making it a distinctive and collectible mineral.