Seashell Fragment (Aragonite/Calcite)

Physical Properties

Hardness: 3.0-3.5 on Mohs scale. Color: White to cream. Luster: Pearly to dull. Crystal structure: Orthorhombic (Aragonite) or Trigonal (Calcite). Specific gravity: 2.7-2.9.

Formation & Geological History

Biogenic sedimentary process. Formed as part of a marine bivalve or gastropod's exoskeleton through precipitation of minerals from seawater. This fragment has been weathered and smoothed by wave action.

Uses & Applications

Shell fragments are used in soil conditioning, as a source of lime, for aquarium substrate, and in decorative jewelry or crafts.

Geological Facts

While biologically produced, seashells are major contributors to the formation of limestone and marble over geological timescales. They are considered biogenic minerals.

Field Identification & Locations

Identify by its curved layered structure, pearly interior, and reaction (fizzing) if exposed to a mild acid like vinegar. Commonly found on coastal beaches.

Identified on: 4/15/2026

Mode: Standard