Micro-World Gems & Gemology, Winter 2017, Vol. 53, No. 4

Quarterly Crystal: Shattuckite
in Quartz

Shattuckite typically forms aggregates of circular to spherulitic masses composed of acicular crystals
Figure 1. Measuring 41.27 mm and weighing 164.63 ct, this quartz crystal cluster contains
a phantom composed of an abundance of deep blue radial concretions of shattuckite,
forming a rich blue felted mat. Photo by Kevin Schumacher.

For our “Quarterly Crystal” in the Micro-World column, we are always searching for unusual crystal specimens that contain interesting mineral inclusions and other micro-features worthy of description. This quarter’s offering is an intergrown cluster of quartz crystals that play host to a rich blue deposition of the orthorhombic copper silicate mineral shattuckite, which typically forms aggregates of spherulitic to circular masses composed of acicular crystals (figure 1). The 41.27 mm long quartz crystal grouping (figure 2) came from the Kandesei mine in the Kunene region of Namibia and was acquired from Jordi Fabre (Fabre Minerals, Barcelona).

Figure 2. As an inclusion in quartz, shattuckite typically forms aggregates of circular to spherulitic masses composed of acicular crystals. Photomicrograph by Nathan Renfro; field of view 3.55 mm.

The inclusions were situated in the quartz crystals in the form of phantoms that developed through the deposition of the shattuckite on the surface. Laser Raman microspectrometry identified the phantom layers as shattuckite. As the quartz continued to grow, the shattuckite was captured as inclusion phantom planes tracing the form of the original quartz host.

Named for the type locality—the Shattuck mine in Bisbee, Arizona—shattuckite is a medium to deep blue mineral with a silky luster. A secondary mineral in oxidized copper deposits, shattuckite is often found together with ajoite, chrysocolla, and malachite, in addition to quartz.

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