Spessartines on Smoky Quartz
I’ve collected some cool rocks from local waterways in the past, but I’ve always wanted to maintain a more serious mineral collection. I decided to curate some specimens from around the world instead of only self-collecting local material.

I acquired this cluster of spessartine garnets and smoky quartz crystals. The matrix is microcline with biotite inclusions which contribute an attractive sparkle. My favorite part is the chunky garnet growing on top of a nicely terminated quartz.

I’m a huge fan of garnets. They’re inexpensive, durable, appear in many colors, and have a high refractive index. Spessartines are a variety of garnets with an orange-red hue, which I believe is caused by manganese.
Quartz is a very common mineral in part because its hardness makes it erode extremely slowly, and also because it’s made of the two most common elements in the crust (silicon and oxygen). The color of smoky quartz is caused by an interesting process where aluminum impurities transfer electrons to neighboring cations in the presence of radiation. High temperatures can change the color to greens, yellows, and browns.

This cluster was collected from the Wushan Spessartine Mine in Fujian, China. However, I’m not sure whether it was from the Tongbei site or the Yunling site.
These minerals formed together out of intrusive granite at the subduction of the Paleo-Pacific Plate underneath the Eastern Block of the North China Block.
Further Reading:
Nunes, Eduardo Henrique Martins and Lameiras, Fernando Soares The optical absorption of gamma irradiated and heat-treated natural quartz. Materials Research [online]. 2005, v. 8, n. 3 , pp. 305-308. Available from: https://doi.org/10.1590/S1516-14392005000300014. Epub 10 Oct 2005. ISSN 1980-5373.
Qiu, J., Wang, D., McInnes, B., Jiang, S., Wang, R., & Kanisawa, S. (2004). Two subgroups of A-type granites in the coastal area of Zhejiang and Fujian Provinces, SE China: Age and geochemical constraints on their petrogenesis. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 95(1-2), 227-236. doi:10.1017/S0263593300001036
Zeng, G., He, Z.-Y., Li, Z., Xu, X.-S., and Chen, L.-H. (2016), Geodynamics of paleo-Pacific plate subduction constrained by the source lithologies of Late Mesozoic basalts in southeastern China, Geophys. Res. Lett., 43, 10,189– 10,197, doi:10.1002/2016GL070346.