First of all, let’s talk about growth: the chemical elements that are available during the growth of a crystal might change slightly over time. Sometimes, it doesn’t show unless you do actual chemical analyses, and notice slight variation in minor elements (changes in the 1% level or less). Some other times, you can actually see it, as the color of the mineral changes, such as for these two tourmalines.
Zoned liddicoatite tourmaline (22 x 17 x 0.7 cm); Anjanabonoina mine, Antsirabe,
Antananarivo, Madagascar.
Bi-color tourmaline (10.7 x 3.7 x 3 cm); Kunar, Afghanistan (donor: Savinar).
Click to read more about preferential differentiation on different gems!
