Ammolite

Ammolite Gemstones
The color-producing shell layer of Ammolite is usually very thin (often less than one millimeter) and attached to a dark gray to brown base of shale or siderite. Exceptional pieces can be cut into gems without stabilization.

Most Ammolite is used to produce triplets. These are made by backing the fragile iridescent material with a thin slab for stability and topping it with a transparent cover for protection.

Clear quartz or spinel can be used for the transparent cover. Black shale or another material can be used for the backing. Some Ammolite is made into doublets, which only requires adding a backing or transparent cover as needed. Many stones are impregnated with epoxy for stability.

The best stones: 1) produce a vivid display of multiple colors; 2) have a strong iridescence that can be observed from a wide range of angles; and, 3) have a pleasing pattern of color with minimal interruption by gaps, inclusions or fractures.

The highest quality rough is usually cut into freeform shapes to produce gems of maximum carat weight. These are used in designer jewelry. Other grades of material are cut to standard shapes for use in commercial jewelry.

When assembled stones include a clear cap, it normally has a minimum amount of doming to provide the best view of the Ammolite below. A small number of stones have a faceted cap for customers who like that appearance. Uncapped stones are best used in earrings, brooches, pins and pendants where abrasion and impact are less likely. This is because the material is soft (H: 3.5 to 4), brittle, and can cleave upon impact. this was all created by Geology.com! {| class="wikitable"
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Physical Properties of Ammolite
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 * Chemical Classification
 * Carbonate
 * Color
 * Iridescent colors that can traverse the entire spectrum - red, orange, yellow, green, blue, indigo and violet. Red and green are the most common colors.
 * Luster
 * Vitreous, accepts a bright polish
 * Diaphaneity
 * The gem layer is transparent to translucent.
 * Cleavage / Fracture
 * Brittle with distinct cleavage
 * Mohs Hardness
 * 3.5 to 4
 * Specific Gravity
 * 2.6 to 2.9
 * Diagnostic Properties
 * A thin layer of iridescent color, often with a fractured appearance, on a base of siderite or shale
 * Chemical Composition
 * CaCO3
 * Mineral Composition
 * Aragonite, usually on a base of siderite or shale
 * Crystal System
 * Orthorhombic
 * Uses
 * Gemstone
 * }
 * Chemical Composition
 * CaCO3
 * Mineral Composition
 * Aragonite, usually on a base of siderite or shale
 * Crystal System
 * Orthorhombic
 * Uses
 * Gemstone
 * }
 * Uses
 * Gemstone
 * }