662 REPORT OF NATIONAL MUSEUM, 1897. 



anbydrons aud hydrous. The phosphates may crystallize with a fluor- 

 ide as ill apatite, with a chloride as in pyromorphite, or with a hydroxyl 

 as in triploidite. 

 The following are examples of this type : 



Monazite — Burke County, North Carolina. (Cat. No. 49463, U.S.N.M.) 

 Apatite— Hammond, St. Lawronce County, New York. (Cat. No. 49780, U.S.N.M.) 

 Pyromorphite — Wheatley mine, Phoenixville, Pennsylvania. (Cat. No. 12572, 



U.S.N.M.) 

 Triploidite — Branchville, Connecticut. (Cat. No. 49576, U.S.N.M.) 

 Variscite— Montgomery County, Arkansas. (Cat. No. 45194, U.S.N.M.) 

 Cacoxenite — Nobles mine, Lancaster Couuty, Pennsylvania. (Cat. No. 49075, 



U.S.N.M.) 

 Autunite — Stoneham, Maine. (Cat. No. 45795, U.S.N.M.) 



Oxygen salts, arsenates. — The arsenates include all those compounds of 

 oxides with oxides whose negative parts are taken by arsenic pentox- 

 ide. The arsenates are similar to the phosphates in molecular structure, 

 and, like them, the majority are either isomorphic modifications or basic 

 salts, both with and without water of crystallization. Further, they may 

 consist of a combination of a chloride, fluoride, or hydroxyl with an 

 arsenate. As a class they present many analogies to the phosphates, 

 and like salts, as a rule, are isomorplious. The few rare native antimo- 

 nates, together with chloriferous antimonites and arsenites, are here 

 included with the arsenates. 



Examples of this type are shown in the following specimens: 



Mimetite— Leadville, Colorado. (Cat. No. 51362, U.S.N.M.) 

 Tyrolitc— Mammoth min<', Tintic, Utah. (Cat. No. 48121, U.S.N.M.) 

 Conichalcite — American Eagle mine, Tintic, Utah. (Cat. No. 48244, IT.S.N.M.) 

 Sforodite— Red Mountain, Colorado. (Cat. No. 81190, U.S.N.M. ) 



Oxygen salts, sulphates. — The sulphates — compounds of oxides with 

 oxides in which the sole or principal negative constituent is sulphur 

 trioxide — may be simple or isomorphic combinations or basic salts, 

 either anhydrous or hydrous. They may also crystallize with chlorides 

 or carbonates. The few native tellurates and selenates, compounds 

 analogous to the sulphates, whose negative parts are respectively taken 

 by telluric or selenic oxide, together with those compounds in which 

 the more negative part is taken by either tellurous or selenous oxide, 

 are here grouped with the sulphates. 



The following specimens are examples of this type: 



Barite— DufUm, England. (Cat. No. 49799, U.S.N.M.) 

 Selenite— I'ort Ellsworth, Kansas. (Cat. No. 82376, U.S.N.M.) 

 Brochantite — United Verde mine, Yavapai County, Arizona. (Cat. No. 48784, 

 U.S.N.M.) 

 Alunite — Rosita Hills, Custer County, Colorado. (Cat. No. 51710, U.S.N.M.) 

 Alnnogeu — Esmeralda County, Nevada. (Cat. No. 17643, U.S.N.M.) 

 Hanksite— San Bernardino County, California. (Cat. No. 81217, U.S.N.M.) 



Oxygen salts, chronuites. — The chromates — compounds of chromium 

 trioxide with other oxides — are isomorphous with the corresponding 

 sulphates. The class has but few representatives among minerals. 



