Vivianite

Object/Artifact

-

Crater Rock Museum

Name/Title

Vivianite

Entry/Object ID

2009.62.30

Description

Chemical Composition: Fe3(PO4)2-(H2O)8 Crystal System: Monoclinic System Description: Common Name: Vivianite Chemistry: Fe3(PO4)2-(H2O)8, Hydrated Iron Phosphate Group: Phosphates Location: Cameroon, West Africa Description: Very dark crystal all most black looking but is actually a greenish purple. 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. Best Field Indicators are color and reaction to light, flexible crystals and crystal habit. Fracture: splintery Hardness: 2 Gypsum Luster: Vitreous Occurrence: It is formed by the alteration of ore deposits near the surface, or of primary phosphates in pegmatites. Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone. Rock Type: Sedimentary Specific Gravity: 2.6+ Streak: White / bluish green Texture: Microcrystaline Variety: 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.

Collection

RAGM Mineral Collection

Acquisition

Accession

2009.62

Source or Donor

Museum Collection of Minerals

Acquisition Method

Donation

Dimensions

Width

2 in

Depth

1-3/4 in

Length

2-3/4 in

Weight

0.71 oz

Dimension Notes

Dimension taken at widest points

Location

Location

Display Case

FS-3-A

Room

Frieda Smith Hall

Building

Crater Rock Museum

Category

Exhibit

Moved By

Ian C.

Notes

Major mineral groups installation