THE MINERAL VIVIANITE

Chemistry: Fe3(PO4)2-(H2O)8, Hydrated Iron Phosphate
Class: Phosphates
Group: Vivianite
Uses: only as a mineral specimen
Specimens

Vivianite has vibrant colors and a nice sparkle. Many clusters are found inside of fossil clam or snail shells or attached to fossil animal bone. Vivianite is not a display case type mineral. Specimens should be kept from long exposure to light as this can darken a specimen to near blackness. The reason for the darkening is from the oxidation of the iron from +2 to +3 and this change yeilds a darker specimen. The oxidation is accelerated by exposure to light. Vivianite can be enjoyed and then should be put back in a dark cabinet to preserve its beauty for years to come.

PHYSICAL CHARACTERISTICS:

Color is blue, green and colorless, darkens upon exposure to light.
Luster is vitreous.
Transparency crystals are transparent to translucent.
Crystal System is monoclinic; 2/m
Crystal Habits include radiating clusters of prismatic, acicular, or fiberous crystals. Also earthy and encrusting masses. Often lines the inside of fossil shells.
Cleavage is perfect in one direction.
Fracture is splintery.
Hardness is 1.5 - 2.
Specific Gravity is approximately 2.6+ (average for translucent minerals)
Streak is white or bluish green.
Associated Minerals are siderite, sphalerite, quartz and some secondary ore deposit minerals.
Other Characteristics: thin crystals are flexible.
Notable Occurances include Maryland and Colorado, USA; Russia; Ukraine and England.
Best Field Indicators are color and reaction to light, flexible crystals and crystal habit.