not a rock (man-made origin)

Blue Sea Glass

Amorphous Silica (Anthropogenic glass)

AI-generated identification · may be incorrect

Hardness: 5-6 Mohs. Color: Deep teal/blue (likely derived from cobalt or copper additives). Luster: Vitreous when wet, often frosted/matte when dry. Crystal Structure: Amorphous (non-crystalline). Cleavage: Conchoidal fracture. Specific Gravity: ~2.4–2.8.

Hardness: 5-6 Mohs
Luster: Vitreous when wet, often frosted/matte when dry

Identified February 23, 2026More not a rock (man-made origin) →

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Physical properties

Formation & geological history

Formed from discarded glass bottles or tableware that ended up in the ocean. Over years or decades, the movement of waves and abrasive action of sand tumbles the glass, rounding its edges and chemically etching the surface to create a matte finish.

Uses & applications

Commonly used in jewelry making (wire wrapping, pendants), beach-themed home decor, and as a popular item for collectors and beachcombers.

Geological facts

Certain colors indicate age; deep blue glass often comes from vintage poison bottles, medicine bottles (like Noxzema or Bromo-Seltzer), or decorative jars from the late 19th and early 20th centuries.

Field identification & locations

Identify by its frosted 'c-shaped' pockmarks on the surface (if genuine) and smooth, rounded edges. Often found on rocky or pebbly shorelines with high wave energy. Authentic sea glass should not have sharp edges or perfectly clear surfaces.