Allanite-(Ce) - Yates Mine, Otter Lake, Pontiac RCM, Outaouais, Quebec, Canada

(CaCe)(AlAlFe²⁺)O[Si₂O₇][SiO₄](OH)

Allanite-(Ce) from the Yates Mine, located in Otter Lake, Quebec, Canada, is a noteworthy example of a rare-earth-element-rich mineral. Allanite-(Ce) belongs to the epidote group and is a complex silicate containing significant amounts of cerium ($Ce$) and other light rare earth elements (LREEs), alongside calcium, aluminum, and iron. Its chemical formula is typically expressed as $(Ce,Ca,Y)(Al,Fe^{3+})_3(SiO_4)(Si_2O_7)O(OH)$, reflecting its intricate structure and composition. The Yates Mine is renowned for producing well-formed allanite-(Ce) crystals in a geologically unique environment.

Appearance and Properties

Allanite-(Ce) at the Yates Mine typically occurs as dark brown to black prismatic crystals with a submetallic to vitreous luster. These crystals are often embedded in a matrix of calcium-rich host rocks such as calcite or apatite, giving them a striking visual contrast. Allanite is moderately radioactive due to its thorium and uranium content, which are often present as minor impurities. The mineral's hardness ranges from 5.5 to 6 on the Mohs scale, and it exhibits a high density, reflective of its rare earth and iron content.

Geological Context

The Yates Mine is situated in the Grenville Geological Province, an area known for its rich deposits of rare earth minerals and skarn-type formations. Allanite-(Ce) forms in the mine's calcium- and silica-rich metamorphic and skarn environments, often in association with minerals like apatite, titanite, calcite, and pyroxene. The high concentrations of rare earth elements and the unique thermal and geochemical conditions of the Grenville Province make the Yates Mine a prime locality for allanite and other REE-bearing minerals.

Significance

Allanite-(Ce) is scientifically significant for its role as a major carrier of rare earth elements in geological systems. These elements are critical for a wide range of high-tech applications, including electronics, renewable energy technologies, and advanced alloys. Allanite’s ability to accommodate a variety of rare earth elements in its crystal structure provides valuable insights into the geochemical behavior of REEs in metamorphic and igneous processes. Specimens from the Yates Mine, with their well-formed crystals and rich associations, are particularly important for studying the mineralogy and geochemistry of rare earth deposits.

Collector’s Appeal

Crystals of allanite-(Ce) from the Yates Mine are prized by collectors for their sharp morphology, contrasting matrix, and provenance from a classic Canadian locality. The mine’s historical significance and the mineral’s radioactive properties add to its intrigue, making it a sought-after specimen for both professional mineralogists and hobbyists. Proper care is required when handling allanite specimens due to their mild radioactivity, but this does not detract from their appeal as exceptional additions to mineral collections.

Conclusion

Allanite-(Ce) from the Yates Mine exemplifies the fascinating intersection of mineral beauty, geological significance, and economic importance. Its role as a rare earth element carrier and its association with the unique geological features of the Grenville Province highlight its importance in understanding REE mineralization. Specimens from the Yates Mine remain a testament to Canada’s rich mineralogical heritage and continue to be highly valued in the world of mineral collecting and research.

Approx. specimen size: 75mm x 35mm x 10mm

Approx. activity on an SE International Ranger EXP: 1000 cpm