Gem News International Gems & Gemology, Summer 2021, Vol. 57, No. 2

Mobile Inclusions in a Decorative Quartz Object


This brown negative crystal has an irregular shape.
Figure 1. A partial view of the long irregularly shaped brown negative crystal running along the length of its quartz host. Photomicrograph by Lai Tai-An Gem Lab; field of view 6.42 mm.

A client recently submitted an interesting transparent, highly polished, barrel-shaped object for identification. It weighed approximately 109.2 g, measured approximately 90 × 37 × 22 mm, and clearly exhibited a long brown internal feature (figure 1) containing multi-phase inclusions along the length of the predominantly colorless body. Standard gemological testing resulted in an RI reading of 1.55 (spot) and SG value of 2.61. Microscopic examination revealed fluid, fingerprint, and crystal inclusions typical of a natural growth environment. As a result, the object was identified as natural quartz, which was confirmed by FTIR and Raman analysis.

Numerous tiny brown particles within the negative crystal.
Figure 2. The countless tiny brown particles together with part of the large colorless bubble within the negative crystal. Photomicrograph by Lai Tai-An Gem Lab; field of view 4.57 mm.

However, the most notable feature of this specimen was its unique and impressive mobile inclusion scene. On first impression, the long brown inclusion appeared to be a crystal, but it turned out to be a negative crystal filled with countless tiny mobile brownish particles (figure 2) and a large colorless mobile gas bubble. The mobility of these inclusions within the brown negative crystal was cleverly incorporated into the final design, as the lapidary fashioned the object into a barrel form with flat faces at either end. This allowed the object to be flipped over like an hourglass, so that all the mobile inclusions would be set in motion (figure 3; see video). It was also noted that the gas bubble moved at a faster rate than the tiny particles, which made the object even more captivating. The ambient temperature also appeared to affect the speed at which the inclusions moved—the higher the temperature, the faster the rate.

The tiny brown particles are mobile within the quartz host.
Figure 3. A series of images showing the movement of the tiny brown particles and the large bubble in the barrel-shaped object. The denser particles drop toward the bottom and the bubble rises to the top. When flipped over, the process starts again, reminiscent of an hourglass. Photo by Lai Tai-An Gem Lab.
Mobile Inclusions in Quartz

Although the identification of this quartz specimen was straightforward, it was a pleasure to see the artistry employed in its fashioning that permitted its inclusions to be easily seen to maximum effect.

Larry Tai-An Lai (laitaiangemlab@gmail.com) operates the Lai Tai-An Gem Laboratory in Taipei.