You will see from the gem table that Andradite has quite a complex chemical composition.
The gem receives its wide variety of colours due to the fact that its complex composition can be a cocktail of manganese, aluminium, titanium or chromium.There are three main members of the Andradite family of Garnets:
Melanite is the black variety of the gem and is not that often seen in jewellery. Its main ingredient is titanium and it is often discovered near volcanoes and in particular old lava deposits.
Topazolite is normally yellow in colour and receives its name for its similarity in appearance to Imperial Topaz. The gem has been discovered in Italy and the Swiss canton of Valais (the same location that yields the world’s finest Marcasite), however it is incredibly rare and very hard these days to find.
Demantoid, the green member of Andradite, is a gemstone that is regarded by many as one of the most collectable of all.
The gem group was named after the Brazilian mineralogist José Bonifácio de Andrade e Silva, who in the 1830s discovered four new minerals. Andradite can also be found in Italy, Switzerland, Norway, Mexico and America.