Fracture

Physical Properties

Definition

The way a gemstone breaks along non-planar surfaces that do not follow the crystal structure, described by the texture and shape of the broken surface.

Detailed Explanation

Fracture types include conchoidal (smooth, curved — characteristic of glass and quartz), hackly (jagged, like torn metal), splintery (fibrous or splintered appearance), and uneven (irregular). Unlike cleavage, fracture can occur in any direction. Obsidian and glass display classic conchoidal fracture, which prehistoric humans exploited to produce sharp flint tools. Opal, being amorphous, shows conchoidal fracture with no cleavage, while jade (nephrite and jadeite) shows a splintery, interlocking texture that gives it exceptional toughness despite moderate hardness.

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