Vanadinite - Large Chunk (2-3 inch)

Vanadinite is a highly uncommon geologlical formation, known as a secondary mineral since it only occurs as a result of chemical alterations to a pre-existing mineral, specifically the lead ore known as Galena.  Vanadinite is a brittle and dense mineral, and tends to be found in the form of hexagonal red crystals.  It is used in industrial applications, and can be used as a minor source of lead.  Vanadinite was discovered in Mexican mines in the 19th century, and was originally thought to contain a new element, though this discovery proved to be a duplicate of a metal discovered earlier by Andrés Manuel del Río that he had named 'brown lead'.  Vanadinite is generally bright-red or orange-red in colour, although sometimes brown, red-brown, grey, yellow, or colourless. Its distinctive colour makes it popular among collectors of minerals. The streak can be either pale yellow or brownish-yellow. Vanadinite may be translucent, transparent, or opaque, and its lustre can range from resinous to adamantine. Vanadinite is anisotropic, meaning that some of its properties differ when measured along different axes.  Makes an excellent addition to any earth science classroom for decoration, or for inclusion in a rock or mineral collection.

Vanadinite Specifications:

Color: Bright red, orange-red, red-brown, brown, yellow, grey or colourless
Color of streak: Brownish-yellow
Moh’s hardness: 3-4
Specific gravity: 6.8–7.1
Cleavage: None
Fracture: Uneven to conchoidal
Crystal system: Prismatic or nodular; may be acicular, hairlike, fibrous; rarely rounded, globular
Chemical composition: Pb5(VO4)3Cl
Transparency: Transparent, translucent, or opaque
Refractive index: nω = 2.416, nε = 2.350
Fluorescence: None