摘要
青岛海滩砂中的曲晶石(Cyrtolite)晶形完好，除了具有锆石的一般性质外，以富含Th、Y、Yb、Hf、La、Re和Sc等稀有、稀土、放射性元素为特征，是青岛海滩重矿物砂中的重要稀土元素矿物之一。
The cyrtolite is characterized by high contents of Th, Y, Yb, Hf, La, RE and Sc elements in the heavy mineral sands on Qingdao beach.In this paper the forms, physical properties, X-ray data, chemical components and infrared absorption spectra of the cyrtolite are described, and the sources of the cyrtolite in the beach sands are discussed.The mineral colours are brown and dark brown. The crystal range from o.5 to 1.0mm. Hardness<7. Specific gravity 4.26-4.75. Uniaxial ( + ). The interference colour is first-order. No≈1.838.Its main components. SiO2 28.16. A12O3 9.81. Fe2O3 3.55.TiO2 0.30, CaO 0.31, MgO 0.08, MnO3 0.04, P2O5 0.59, RE 2.85, ThO2 2.73, Sc 0.0078, ZrO2 50.62, Hf 0.91, H2O 0.90 and H2O- 0.60. The contents of Zr and Hf are similar to the zircon, and high contents of Y, Yb and La have been found. IR absorption curves include three principle bands at 440, 610 and 900 cm-1, and two subordinate bands at 310 and 390cm-1. On the basis of calculated H/M value the mineral is considered as a lightly metamic zircon. X-ray powder data show that it is a cyrtolite.The relationship between variation of the mineral content and distribution of the lithofacies of Laoshan Granite suggest that the zircon is related to the biotite-granite, Whereas the cyrtolite is derived from the alkali-alaskite.
