Micro-World Gems & Gemology, Summer 2025, Vol. 61, No. 2

Mystery Pebbles in Quartz

John I. Koivula, Nathan Renfro, and Maxwell Hain

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Figure 1. This 150.97 ct quartz crystal hosts pebbles of an amphibole, stacked like rocks in a stone wall. Photo by Annie Haynes.
 
Figure 1. This 150.97 ct quartz crystal hosts pebbles of an amphibole, stacked like rocks in a stone wall. Photo by Annie Haynes.

Sometimes strange specimens come to us for examination and publication in the Micro-World column. The transparent to opaque, partially polished crystal of doubly terminated rock crystal quartz shown in figure 1 is one such example.

The crystal weighed 150.97 ct and measured 55.52 × 24.59 × 19.13 mm. Raman analysis revealed that the pebbles embedded in the quartz were composed of a mineral in the amphibole supergroup, though the exact type of amphibole remains unknown.

Figure 2. The fibrous felted texture of the amphibole pebbles was revealed under magnification. Photomicrograph by Nathan Renfro; field of view 20.57 mm.
 
Figure 2. The fibrous felted texture of the amphibole pebbles was revealed under magnification. Photomicrograph by Nathan Renfro; field of view 20.57 mm.

Thought to have come from the Fengjiashan mine in Daye County, Hubei Province, China, the crystal contained numerous opaque light gray to white and yellowish fibrous rounded pebbles with a felted texture, in various sizes up to 12 mm, as shown in figure 2. Overall, the inclusion scene had the appearance of rocks stacked in a stone wall. How the inclusions formed in this way is a gemological mystery, but they certainly provided us with a very photogenic specimen.

John I. Koivula is analytical microscopist, Nathan Renfro is senior manager of colored stone identification, and Maxwell Hain is a staff gemologist, at GIA in Carlsbad, California.