Isobana (Melithaer Coral / Melithaer)
Isobana refers to the skeletal axis of coelenterates that form coral reefs; it is not strictly classified in academic terms. It is used as a material for beads and carvings, and its raw, branch-like form is sometimes called "Iso-aka coral" (Isobana red coral). It is characterized by a unique appearance with light-colored veined patterns, and beautiful specimens in deep red are sometimes produced.
Beautiful red Isobana coral
Basic Information
| English Name | Melithaer or Melitodes |
|---|---|
| Japanese Name | Isobana Coral |
| Chemical Composition | CaCO3 + MgCO3 + organic substances like carotene |
| Classification | Aggregate of fine crystals (hexagonal system) |
| Hardness | 3.5–4 |
| Specific Gravity | Approx. 2.25 |
| Transparency | Opaque |
Features & Variations
- Iso-aka Coral: Raw, branch-like form.
- Veined Patterns: Characterized by light-colored veined streaks.
- Porosity: The surface is porous, densely packed with countless small, net-like holes.
- Yellow-brown Striping: The presence of yellow-brown stripes is a key identification point.
Origin, Aliases, Treatments & Similar Stones
Typical Origin: Coral reef areas of the Pacific and Indian Oceans.
Aliases: Apple coral, sponge coral, tabula coral (used for pipe organ coral).
Treatments: Impregnation (impregnating colorless or colored synthetic resin into the pores of the skeletal structure), coating (covering the surface with a resin film to enhance luster and durability).
Similar Stones: Red coral (resembles the branching form when in a raw state).
Note: As there are many confusing names in the market, it is important to confirm the origin when purchasing. Deep red specimens are considered rare and highly valuable.