Final answer:
The gemstone variety of Andradite includes types such as demantoid, melanite, and topazolite, and obtains its color in a manner similar to other gemstones like ruby and emerald, through trace impurities in the crystal lattice.
Step-by-step explanation:
The gemstone variety of Andradite is part of the garnet group and is known for several types, including the highly lustrous demantoid, which is characterized by a vivid green color and is highly prized among gemstones. Another variety is melanite, which is notable for its black appearance. Yet another is topazolite, which ranges in color from yellow to brownish-yellow. Gemstones like andradite gain their color from trace impurities within their crystal structure, similar to how ruby and emerald acquire their respective red and green hues due to the presence of small amounts of Cr³+ ions substituting for Al³+ in the minerals' metal oxide lattice.