Fossiliferous Limestone
Calcite var. Fossiliferous Limestone (Biomicrite) · Decorative Stone / Mineral Specimen
Crystal System
Trigonal (individual calcite crystals); massive, microcrystalline, or granular structure
Mineral Group
Carbonates (Calcite group)
Chemical Formula
CaCO3 (Calcium Carbonate) with possible impurities of SiO2 and organic carbon
Formation Process
Sedimentary (Biogenic): Formed by the accumulation and lithification of marine skeletal remains, shell fragments, and organic matter in low-energy marine environments
About This Crystal
A polished sphere displaying a tan to light-brown fine-grained matrix embedded with numerous darker fossil inclusions. The surface shows cross-sections of ancient shells, crinoids, or gastropods. It has an opaque transparency and a vitreous to dull luster depending on the polish quality.
Physical Characteristics
Color: Beige, tan, and brown; Streak: White; Cleavage: Perfect rhombohedral in calcite crystals, though generally absent in massive form; Fracture: Uneven to subconchoidal; Specific Gravity: 2.7; Fluorescence: Often fluoresces dull orange or yellow under UV light.
Optical Properties
Singly and doubly refractive (calcite); Refractive Index: 1.486–1.658; Birefringence: 0.172; No pleochroism; Non-dispersive; Opaque matrix prevents significant optical phenomena.
Hardness & Durability
Origin Region
Globally abundant; notable sources include the Jura Mountains (France/Switzerland), Morocco, and the Midwestern United States (Indiana/Kentucky)
Hardness & Durability
Mohs Hardness: 3.0; Toughness: Poor to fair; Highly sensitive to acids; Low wearability for jewelry, primarily used for ornamental objects or beads.
Care & Maintenance
Clean only with warm, soapy water and a soft cloth. Avoid all acidic cleaners (vinegar, lemon), ultrasonic cleaners, and steam. Store separately to avoid scratching by harder minerals like quartz.
Rarity & Value
Common; Value is generally low, determined by the intricacy of fossils and quality of the polish. Larger spheres or those with rare fossil species may command higher prices.
Special Characteristics
Fossil inclusions: Contains visible macro-fossils that provide a glimpse into ancient marine life; reacts violently (effervesces) with dilute hydrochloric acid.
Lore & History
Historically used as a building material and for carving. In metaphysical lore, it is believed to be a stone of 'endurance' and 'past-life' recall due to the ancient organic matter preserved within. Traditionally associated with the Root Chakra for grounding.