Micro-World Gems & Gemology, Spring 2016, Vol. 52, No. 1

Quarterly Crystal: Quartz and Lazulite

Quartz crystals with deep blue lazulite
Figure 1. Recovered from Canada’s Yukon Territory, these doubly terminated parallel-growth quartz crystals are decorated with deep blue crystals of lazulite. This specimen weighs 76.19 ct and measures 36.12 × 22.24 × 16.95 mm. Photo by Kevin Schumacher.

Before a gemstone is fashioned by a lapidary, it enters the gem trade in its natural state, in a form generally referred to as “rough” or “gem rough.” Not all rough is gem quality, nor is most so-called rough appropriate for fine mineral collections. Only a very special piece of rough is suitable for gem use or fits the visual definition of a fine mineral specimen. When such crystals are encountered it then becomes a difficult decision, often financially based, whether to leave them in a natural state or fashion them into polished gems.

Our new “Quarterly Crystal” section of the Micro-World column will feature very attractive inclusion-bearing minerals that could also be fashioned by a skilled lapidary into a gem or a polished inclusion study block. The quartz and lazulite specimen shown in figure 1 is one such mineral.

These parallel-growth, doubly terminated glassy quartz crystals were recovered from Rapid Creek in the Dawson mining district of Canada’s Yukon Territory. While this is a nearly perfect mineral specimen, hosting swarms of deep blue lazulite crystals both on the surface and within (figure 2), it also makes a remarkable piece for any inclusionist’s collection. Since this is a very uncommon mineral association from the locality, whether to polish it is a difficult decision. Fortunately, this dilemma can often be avoided with a simple trick: A small drop of mineral oil placed on the surface serves as a temporary window through which the inclusions may be observed and photographed.

Lazulite inclusions using partial immersion technique
Figure 2. Inclusions of lazulite in this Canadian quartz were photographed using a partial immersion technique. A drop of mineral oil was placed on the surface to create a temporary window into the interior. Photomicrograph by Nathan Renfro; field of view 4.45 mm.

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