Ammonite (Goniatite)
Ammonoidea (Subclass), typically preserved as Aragonite or Calcite · Fossil (Organic Gem/Mineral Specimen)
Crystal System
Orthorhombic (Aragonite) or Trigonal (Calcite); typically presents as a planispiral coiled cephalopod fossil
Mineral Group
Carbonates
Chemical Formula
CaCO3 (Calcium Carbonate) with possible inclusions of Pyrite (FeS2) or Silica (SiO2)
Formation Process
Sedimentary. Forms through permineralization or recrystallization of an extinct marine mollusk's shell within seafloor silt/mud under pressure over millions of years.
About This Crystal
Two halves of a split nodule showing a coiled cephalopod fossil. The shell chambers (septa) are visible, filled with crystalline material. Luster is earthy on the matrix and vitreous to sub-adamantine on the crystalline fossil portions. Color is typically brown to iron-oxide orange with white/translucent chambers.
Physical Characteristics
Color: Brown matrix, white/grey fossil; Streak: White; Cleavage: None (fossilized); Fracture: Conchoidal to uneven; Specific Gravity: 2.7–2.9; Fluorescence: Sometimes white or yellow under UV if calcite-rich.
Optical Properties
Matrix is opaque; crystalline chambers may show double refraction (if calcite) and vitreous luster. High-quality specimens (Ammolite) show iridescent play-of-color, though these appear to be standard polished fossils.
Hardness & Durability
Origin Region
Morocco (Anti-Atlas Mountains), Madagascar, and various worldwide marine sedimentary deposits
Hardness & Durability
Mohs Hardness: 3.5 to 4.0. Brittle and sensitive to acids and impacts. Not recommended for high-wear jewelry unless protected.
Care & Maintenance
Avoid acidic cleaners (vinegar, lye), ultrasonic cleaners, and steam. Clean only with warm soapy water and a soft cloth. Store away from harder minerals like quartz or diamonds to prevent scratching.
Rarity & Value
Common. Small split nodules (especially Goniatites from Morocco) are widely available. Value is determined by clarity of the suture lines, size, and presence of internal mineralization or iridescence.
Special Characteristics
Features visible internal septa (chamber walls) and a distinct spiral Fibonacci growth pattern. This specific specimen is a 'split pair' or 'matching halves' from a single nodule.
Lore & History
Historically known as 'Snakestones' in medieval Europe, believed to be petrified coiled snakes. Metaphysically, they are associated with the Root Chakra and symbolize evolution, longevity, and the cycle of life due to their spiral shape.