It reacts readily with acids, with elemental boron, carbon, nitrogen, phosphorus, selenium, silicon, or sulfur, and with the halogens. The oxide and the boride are used in electronic vacuum tubes. The oxide is added to optical glass to increase its alkali resistance and refractive index. Although lanthanum is not found uncombined in nature, it occurs in the rare-earth minerals monazite and bastnasite. Lanthanum may be prepared by reduction of lanthanum fluoride with calcium metal.
Natural lanthanum is a mixture of two stable isotopes.
Lanthanum was discovered in the form lanthanium oxide, called lanthana, in 1839 by C. G. Mosander. Listing from Electric Library , a pay service. No relevant pictures or maps found. The Columbia Electronic Encyclopedia, Sixth Edition Copyright 2000, Columbia University Press. Copyright 2001 Infonautics Corporation .