镧通常存在于独居石、硅铈石、褐帘石、镧石、氟碳铈矿及氟碳酸钙铈矿等矿物中,在这些矿物内镧的含量除铈以外比其他希土元素都要高一些,如在独居石中就含 La_2O_3 14～30%。氧化镧常用来制造无色光学玻璃,能使玻璃明亮洁净,对还原焰无感应,当焙烧和在阳光下不变色。在制坦克潜望镜的棱镜中含有60%氧化镧,它能使棱镜的折射率介于好的燧石玻璃与金刚石之间,在陶瓷工业方面镧与其他希土混合物用来制备温度系数等于零的绝缘体。含镧希土所制得的玻璃电极性能较好。在冶金工业方面常用含镧混合金属以改进电炉钢与平炉钢的物理性质,在镍铬合金中添加含镧的混合希土就 Lanthanum is commonly found in minerals such as monazite, cristobalite, polydatin, lanthanum, bastnaesite and bastnaesite, in which the content of lanthanum is higher than other rare earth elements except for cerium Some, such as in monazite containing La_2O_3 14 ~ 30%. Lanthanum oxide is often used to make colorless optical glass, which can make the glass bright and clean without any reaction to the reduction flame. When roasted and not exposed to sunlight, it does not change color. The 60% lanthanum oxide contained in the prism of the periscope makes it possible to make the refractive index of the prism between good flint glass and diamond. In the ceramic industry, a mixture of lanthanum and other rare earths is used to prepare an insulator with a temperature coefficient equal to zero. The glass electrode made of lanthanum-containing rare earth has better performance. In the metallurgical industry commonly used lanthanum-containing mixed metals to improve the physical properties of electric furnace steel and open hearth steel, nickel-chromium alloy added in the mixed with rare earth lanthanite