Rock Identifier
Acrylic or Resin (Synthetic Imitation) (Polymethyl Methacrylate (PMMA) or Polyepoxide) — Synthetic/Man-made Polymer
Synthetic/Man-made Polymer

Acrylic or Resin (Synthetic Imitation)

Polymethyl Methacrylate (PMMA) or Polyepoxide

Hardness: 3-4 (Mohs scale); Color: Swirled translucent green and black; Luster: Vitreous to pearly; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific Gravity: 1.1 - 1.2 (very light)

Hardness
3-4 (Mohs scale)
Color
Swirled translucent green and black
Luster
Vitreous to pearly
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Physical properties

Hardness: 3-4 (Mohs scale); Color: Swirled translucent green and black; Luster: Vitreous to pearly; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific Gravity: 1.1 - 1.2 (very light)

Formation & geological history

This is a man-made industrial product formed through chemical polymerization. It is liquid resin poured into a mold, colored with pigments or micas to create a 'chatoyant' or 'marbled' effect, and cured to hardness. It is not a geological specimen.

Uses & applications

Used primarily in the manufacturing of gaming accessories (tabletop dice), jewelry, knobs, and decorative hobbyist items.

Geological facts

This specific shape is an icosahedron, commonly known as a d20 (20-sided die). While it mimics the look of minerals like Malachite or Jade, the swirling pattern is a result of mixing different shades of liquid plastic before setting.

Field identification & locations

Can be identified in the field as synthetic by its very light weight compared to stone, a 'plastic' sound when tapped against teeth, and the presence of air bubbles or mold lines. It is found in hobby shops rather than geological deposits.

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