Scheelite Mineral Overview

• Mineral name: Scheelite
• Mineral class: Oxide (tungstate)
• Chemical formula: CaWO₄
• Crystal system: Tetragonal
• Mohs hardness: 4.5–5
• Color range: Colorless, white, gray, yellow, orange, brown
• Luster: Vitreous to adamantine
• Streak: White
• Cleavage: Distinct
• Fracture: Uneven to subconchoidal
• Specific gravity: Approximately 5.9–6.1 (very high)
• Transparency: Transparent to opaque
• Common locations: China, Austria, United States, Russia, Bolivia
• Uses: Primary ore of tungsten, collector mineral
• Similar minerals: Stolzite, wulfenite, powellite

Naming and Classification

Scheelite is a calcium tungstate mineral and one of the most important ores of tungsten. It is named after Swedish chemist Carl Wilhelm Scheele, who discovered tungsten as an element.

It belongs to a group of tungstate minerals and is structurally related to:

• Stolzite (PbWO₄) (lead tungstate)
• Powellite (CaMoO₄) (calcium molybdate)

Physical and Optical Characteristics

Scheelite typically forms well-shaped crystals, commonly appearing as:

• Tetragonal dipyramids
• Short prismatic crystals

It may also occur in massive or granular forms.

Color varies widely, including:

• Colorless or white (pure material)
• Yellow to orange
• Brown or gray (due to impurities)

The luster ranges from vitreous to slightly adamantine, especially in transparent crystals. With a hardness of 4.5 to 5, scheelite is relatively soft and can be scratched by harder silicates.

It has distinct cleavage, and fracture is uneven to subconchoidal.

A notable property is its high density, making specimens feel heavier than expected.

Fluorescence

Scheelite is well known for its strong fluorescence under ultraviolet (UV) light, typically showing:

• Bright blue fluorescence

This property makes it useful in:

• Prospecting for tungsten deposits
• Identifying specimens in the field

The intensity of fluorescence can vary depending on impurities, particularly molybdenum content.

Chemical Composition and Structure

Scheelite is composed of:

• Calcium (Ca)
• Tungsten (W)
• Oxygen (O)

It contains the tungstate ion (WO₄), which forms a tetrahedral unit within the crystal structure.

It forms a solid solution series with:

• Powellite (CaMoO₄)

where tungsten (W) can be partially replaced by molybdenum (Mo).

Formation and Geological Occurrence

Scheelite forms in several geological environments, most commonly:

Skarn Deposits

• Contact zones between igneous intrusions and carbonate rocks
• High-temperature conditions

Hydrothermal Veins

• Deposited from tungsten-rich fluids

Metamorphic Environments

• Occurs in high-temperature metamorphic rocks

It is commonly associated with:

• Quartz
• Calcite
• Wolframite
• Garnet
• Pyroxene

These associations reflect tungsten-rich geological systems.

Common Locations

Scheelite is found in major tungsten-producing regions:

• China: Largest global producer
• Austria: Classic European locality
• United States: California and Nevada
• Russia and Bolivia: Important deposits

Many of these locations host significant tungsten mining operations.

Uses and Practical Significance

Scheelite is a major ore of tungsten, which is used in:

• Hard metals and alloys: Cutting tools, drill bits
• Electronics: Electrical components
• Lighting: Tungsten filaments (historically important)
• Industrial applications: High-temperature and high-strength materials

Its economic importance is tied directly to tungsten demand.

Similar and Related Minerals

Scheelite can resemble other tungstate and molybdate minerals:

• Stolzite: Denser and often more yellow to brown
• Wulfenite (PbMoO₄): Typically forms thin tabular crystals
• Powellite: Similar composition but molybdenum-rich

Fluorescence and density are helpful distinguishing features.

Identification Notes for Collectors

• Look for tetragonal crystals or granular material in skarn or vein deposits
• Note moderate softness (4.5–5)
• Check high density (feels heavy)
• Use UV light to observe blue fluorescence
• Consider association with tungsten-bearing minerals

Scheelite is a tungsten-bearing oxide mineral, recognized for its high density, fluorescence under UV light, and importance as a primary source of tungsten, making it both economically significant and of interest to collectors.