Olivine in Oregon Labradorite

Figure 1. This octagonal step-cut labradorite (left) was faceted with an extra-large girdle and a simple faceting pattern to showcase the olivine inclusion trapped inside (right). Photos by Kevin Schumacher.

Gem-quality labradorite from Oregon is typically prized for its red, orange, and green colors, as well as the tiny exsolution platelets of copper that create the phenomenon of aventurescence. Other notable inclusions can also be found in this gemstone from time to time, such as the olivine inclusion in the stone provided by Ken Lack of Gem Net LLC in Grants Pass, Oregon (figure 1). These rare inclusions typically display a greenish yellow bodycolor and compression cracks, indicating a significant amount of strain between the feldspar host and the olivine guest (figure 2; see E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, Opinio Verlag, Basel, Switzerland, 2005, pp. 419, 422). In this example, the stone was reported to have cracked during cutting, presumably due to the strain. This labradorite was cut to showcase the inclusion, making it easy to view from multiple angles.

Figure 2. The olivine inclusion was photographed in an immersion liquid, which wicked along surface-reaching cracks and partially eliminated the reflective interface, allowing better observation inside the olivine. Photomicrograph by Nathan Renfro; field of view 3.83 mm.

Olivine inclusions in labradorite feldspar typically indicate an Oregon origin—if one is lucky enough to find such a rare internal feature.

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