A mineral is a naturally occuring, homogeneous, solid with a crystalline atomic structure. Crystallinity implies that a mineral has a definite and limited range of composition, and that the composition is expressible as a chemical formula. Some definitions of minerals give them as inorganic materials, however both diamonds and graphite are considered minerals, and both are primarily comprised of carbon, which would make them organic. So this leads me, as an engineer, to believe that mineralogists do not have a good, precise definition of a mineral, but rather a loose definition. The definition above, is the most inclusive and would include all substances currently described as minerals. The key items that make something a mineral are occurring naturally, and the definite crystal structure, that is expressible as a chemical formula. Rocks that do not meet this criteria are referred to as amorphis - not having a definite structure or expressible as a chemical formula. Some elements that occur naturally and are minerals are arsenic, bismuth, platinum, gold, silver, copper, and sulphur.

THE DEFINITION OF ORGANIC: Organic chemistry is the study of those substances containing carbon in combination with hydrogen (H), and a few other non metals, namely oxygen (O), nitrogen (N), sulfur (S) and the halogens (F2, Cl2, Br2, and I2).

This specemin shows a few vanadinite crystals on the heavy ore. The white mineral is anglesite, a lead mineral. This specemin has a light yellow streak the others have a white streak.
Vanadinite is a vanadium mineral, and occurs with lead deposits, but usually in small quantities. It has hexagonal crystals, has a hardness of 3 mhos, SG of 6.7 to 7.2, is yellow, red or brown in color. It has a white to pale yellow streak, The specemin in the photo is from Morocco.

The primary use for vanadium is in metallurgy, making high strength steel, it is also used in magnetics, ceramics and as a catalyst.