THE PROPERTIES OF MINERALS. 661 



Oxyf/en salts, titanates. — The titanates — coinpounds of oxides witli 

 oxides whose negative portion is made up solely or chiefly of titanium 

 oxide — may be arranged under the following' groups: Titanates, com- 

 pounds Avhose negative portion is titanium oxide; titanosilicates, 

 compounds whose negative portion is compounded of titanic and silicic 

 oxides; columbotitanates, including those compounds intermediate 

 between the titanates and the succeeding- columbates, and whose nega- 

 tive parts may consist of the oxide of titanium with the oxides of 

 columbium or silicon, with zirconium, etc. 



Examples. 



Iluienite — Chester County, Pennsylvania. (Cat. No. 49959, U.S.N.M.) 

 Titauite— Renfrew County, Canada. (Cat. No. 46566, U.S.N.M.) 

 Hydrotitanit( — Magnet Cove, Arkansas. (Cat. No. 45259, U.S.N.M.) 



Oxygen salts, eoJnmhates and tantalatcs. — The coluinbates and tanta- 

 lates include those compounds of oxides with oxides whose negative 

 parts are taken by the oxides of columbium or tantalum. The intimate 

 relations existing between these compounds require them to be grouped 

 together, there being, in fact, but few native tantalates that do not 

 contain more or less columbium. 



Examples. 



Columbite— Peru, Maine. (Cat. No. 46854, U.S.N.M.) 



Samarskite — Wiseman mine, Mitchell County, North Carolina. (Cat. No. 51222, 

 U.S.N.M.) 

 Tautalite — Coosa County, Alabama. (Cat. No. 45846, U.S.N.M.) 



Oxygen salts,nitat€s. — The nitrates — compounds of oxides with oxides 

 whose negative portion is nitrogen pentoxide — are few and are chiefly 

 salts of sodium, potassium, calcium, and magnesium. There is a single 

 hydrous basic cuprous species and a few double salts. 



Examples. 



Sodaniter— Chile. (Cat. No. 8322s U.S.N.M.; 



O.rygen salts, vanadates. — Under this head are included those min- 

 erals in which vanadium pentoxide constitutes the negative portion. 

 The principal vanadates are vanadinite, a combination of a lead vana- 

 date with a chloride of the same metal, and descloizite, a basic lead 

 vanadate carrying zinc. 



Examples. 



Vanadinite — Aqiui Fria mine, Yavapai County, Arizona. (Cat. No. 48711 

 U.S.N.M.) 



Ucscloizite — Commercial mine, Georgetown, New Mexico. (Cat. No. 48458 

 U.S.N.M.) 



Oxygen salts, phosphates. — Under this head are included the native 

 oxydized compounds of phosphorus, which are without exception com- 

 pounds of oxides with phosphorus pentoxide. The majorit}' of these 

 compounds are either isomorphous modifications or basic salts, both 



