Micro-World Gems & Gemology, Winter 2016, Vol. 52, No. 4

Quarterly Crystal:
Growth Features on Titanite

This Russian titanite is green due to vanadium.
Figure 1. This beautifully formed 17.04 mm titanite crystal from Russia owes its green color to the presence of vanadium. Photo by Kevin Schumacher.

The micro-world of gems and minerals involves not only solid and fluid inclusions, but also significant surface features. If a gem crystal is fashioned into a gemstone by a lapidary artist, most of the surface features of any significance are removed during the process. So when we encounter a beautiful gem crystal, we always take the opportunity to examine the natural surfaces for any interesting evidence of growth or dissolution.

In that regard, we recently studied a beautifully formed titanite crystal (figure 1) from the Ural Mountains in Russia that measured 17.04 × 15.27 × 0.94 mm and weighed 2.35 ct. EDXRF analysis confirmed that its bright green color resulted from the presence of vanadium. As shown in figure 2, examination of the surface using Nomarski differential interference contrast microscopy revealed an abundance of growth features, some with rather dramatic architecture. These were the features targeted for photomicrography.

Growth features observed on titanite surface.
Figure 2. Some of the growth features observed on the surface of the titanite crystal were reminiscent of jagged mountain peaks. Photomicrograph by Nathan Renfro; field of view 0.72 mm.

John I. Koivula is the analytical microscopist at GIA in Carlsbad, California.