Vanadinite is one of the primary ores for the element vanadium [and is also sometimes used as a source for lead]. Vanadium is frequently used as an additive to strengthen steel, with a wide range of industrial applications, so it is in much demand.
Vanadinite is what is known as a "secondary mineral", which means it forms from a pre-existing material - in this case, by the oxidation of lead-bearing rocks.
Please remember that this stone is a lead ore, and all lead ores should be treated with caution. Keep away from young children, and always wash your hands after handling them.