Shattuckite Mineral Overview

• Mineral name: Shattuckite
• Mineral class: Silicate (inosilicate)
• Chemical formula: Cu₅(SiO₃)₄(OH)₂
• Crystal system: Orthorhombic
• Mohs hardness: 3.5–4
• Color range: Deep blue, blue-green
• Luster: Vitreous to silky
• Streak: Pale blue
• Cleavage: Good
• Fracture: Uneven to splintery
• Specific gravity: Approximately 3.8–4.1
• Transparency: Translucent to opaque
• Common locations: Namibia, United States, Democratic Republic of Congo
• Uses: Ornamental stone, collector mineral
• Similar minerals: Azurite, chrysocolla, malachite

Naming and Classification

Shattuckite is a copper silicate mineral, named after the Shattuck Mine in Arizona, where it was first identified.

It belongs to the inosilicate group, meaning its structure consists of chain-like arrangements of silicate tetrahedra, similar to pyroxenes, though chemically distinct due to its copper content.

Physical and Optical Characteristics

Shattuckite typically occurs as:

• Fibrous or radiating aggregates
• Massive or botryoidal forms
• Rarely as well-formed crystals

Its most striking feature is its rich blue to blue-green color, often appearing:

• Deep royal blue
• Turquoise-like blue-green

The luster is vitreous on fresh surfaces but often appears silky due to its fibrous structure.

With a Mohs hardness of 3.5 to 4, shattuckite is relatively soft. It exhibits good cleavage and breaks with a splintery fracture in fibrous material.

Chemical Composition and Color Origin

Shattuckite is composed of:

• Copper (Cu)
• Silicon (SiO₃ chains)
• Hydroxyl (OH)

The intense blue coloration is due to the presence of copper, a common coloring agent in many blue and green minerals.

Formation and Geological Occurrence

Shattuckite forms as a secondary mineral in the oxidized zones of copper deposits.

Typical formation conditions include:

• Weathering of primary copper sulfides
• Interaction with silica-rich solutions
• Low-temperature, near-surface environments

It is commonly associated with:

• Chrysocolla
• Malachite
• Azurite
• Quartz

These associations are typical of copper-rich oxidation zones.

Common Locations

Shattuckite is found in several well-known copper mining regions:

• Namibia: Tsumeb Mine (notable for high-quality specimens)
• United States: Arizona (type locality)
• Democratic Republic of Congo: Copper belt deposits

Namibian material is particularly prized for its color and pattern.

Uses and Practical Significance

Shattuckite is primarily used as an ornamental and collector material:

• Cabochons and beads for jewelry
• Polished stones for display
• Collector specimens

Due to its softness, it is best used in jewelry that is not exposed to heavy wear.

Similar and Related Minerals

Shattuckite can resemble other copper minerals:

• Azurite: Often deeper blue but forms crystals rather than fibrous masses
• Chrysocolla: Typically softer and more variable in color
• Malachite: Green rather than blue

Distinguishing shattuckite often involves:

• Observing fibrous texture
• Noting color and associations
• Chemical or analytical testing

Identification Notes for Collectors

• Look for deep blue to blue-green fibrous or massive material
• Note silky to vitreous luster
• Check moderate softness (3.5–4)
• Observe association with copper minerals
• Consider locality, especially Namibia and Arizona

Shattuckite is a copper silicate mineral, recognized for its intense blue coloration and fibrous texture, and is highly valued as an ornamental stone and collector specimen.