mineral

Vivianite

Vivianite, Fe2+3(PO4)2·8H2O

Hardness: 1.5-2 (Mohs), Color: Colorless to pale green when fresh, turning dark blue to blue-green or black upon exposure to light, Luster: Vitreous to pearly, Crystal structure: Monoclinic, Cleavage: Perfect on {010}

Hardness: 1

Identified July 27, 2026More mineral →

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Physical properties

Formation & geological history

Forms in diverse environments including as a secondary mineral in metallic ore deposits, in deep-sea sediments, lake sediments, bog iron ores, and sometimes replacing organic material in fossils or decaying matter.

Uses & applications

Primarily a collector's mineral due to its beautiful crystal forms and color-changing properties. Used historically as a blue pigment.

Geological facts

Vivianite exhibits striking color alteration; it often starts pale or colorless and darkens to a rich blue or green as the iron within it oxidizes when exposed to light.

Field identification & locations

Identified by its distinctive color change, softness, and perfect cleavage. Common locations include Bolivia, USA (Colorado), England, and Russia. Collectors should keep specimens away from prolonged light exposure to prevent darkening.