Vivianite
Vivianite is an iron phosphate mineral. It is a bluish green, greenish blue, or black mineral found in sedimentary deposits. It crystallizes in the orthorhombic system and typically forms small crystals, although occasionally it may occur in masses and compact aggregates. Vivianite is an important ore of iron, although it is rarely mined due to its overall scarcity and low iron content. Vivianite is not particularly hard or durable, so it is not suitable for jewelry use.
Vivianite forms in sedimentary deposits, mainly in coastal regions or salt flats. It commonly forms in association with other mineral deposits such as iron oxide, pyrite, and glauconite. It can also form in conjunction with organic matter, such as peat and humus. Vivianite is formed through a combination of iron, oxygen, phosphate, and sulfur. It typically forms in association with sulfidic and bacterially-mediated sedimentation environments.
Vivianite was first described in 1817 by the French mineralogist Adolphe Vivian. Vivianite was named after him in honor of his work in mineralogy. He observed this mineral in a sample from a tin ore mine in Lyon, France.
From a practical perspective, vivianite has limited uses due to its low iron content. One notable use of vivianite is in fertilizers. Fertilizers containing vivianite can be used to increase the fertility of soil. Vivianite is also added to concrete mixes, as it improves sulfide tolerance and reduces cracking.
Vivianite has a unique color, which can range from deep blue or green to black or brown. Its color is due to its remarkable ability to absorb and reflect light. When exposed to longwave ultraviolet light, vivianite emits an intense a deep blue fluorescence. In many respects, vivianite exhibits similar appearance to chalcopyrite, another iron mineral.
Vivianite is relatively soft and fragile, ranging from 3 to 3.5 on the Mohs scale. It has a vitreous luster with a white streak and has a transparent to translucent diaphaneity. Vivianite typically forms radiating, prismatic crystals with faces that can be tinged green, gray, blue, or black. It may also form pseudomorphs after other minerals, such as pyrite. Vivianite is found in association with other iron minerals such as hematite and magnetite.
Vivianite is primarily found in sedimentary deposits, primarily in coastal regions or salt flats. It commonly forms in association with other iron minerals, such as pyrite and glauconite. It can also form in conjunction with organic matter, such as peat and humus. Vivianite is formed in sulfur-rich and bacterially-mediated sedimentation environments.
In conclusion, vivianite is an iron phosphate mineral. It is found in sedimentary deposits, typically in combination with other iron minerals. Vivianite has a bluish green, greenish blue, or black color. It is not particularly hard or durable, though it has some practical uses, such as in fertilizers or concrete. Vivianite has a relatively low iron content, so it is not commonly mined for this purpose. Furthermore, it exhibits fluorescence in ultraviolet light, making it an interesting mineral specimen.
