796 



REPORT OF NATIONAL MUSEUM, 1897. 



1 



OXYGEN salts: CLASS, — CHROMATES. 



The chromates, derivatives of H2Cr04, or compounds of chromium 

 trioxide with other oxides, have but few representatives among 

 minerals. Tliey are isoniorphous with the corresponding sulphates, 

 and, like them, may be either normal or basic salts j further, they may 

 crystallize with carbonates and phosphates. 



Tarapaccaite. 

 Crocoite. 



Group 1. 



K2CrO^. 

 PbCrO.. 



Ortborhombic( ' 

 Monocliuic. 



Group 2. 



Phcenicocbroite. Pb(Pb-0)(Cr04),. Ortborbombic(^ 



Jossaite, (Pb,Zn)(Pb,O)(CrO02. Ortborbombic. 



Vauquelinite. (Pb,Cu)(Pb/))(Cr04)> (?) 



Laxmannite. Pb(Pb.:0)(Cr04)2.(Pb,Cu):,(P04),. Monoclinic. 



Bereaovite. 



Group 3. 

 Pb,(Pb,O),(CO:0(CrO4):... 



(?) 



OXYGEN SALTS: CLASS, — MOLYHDATES AND TUNGSTATES. 



The molybdates and tungstates are derivatives of H2M0O4 and 

 H2WO4, or compounds of oxides with oxides whose negative parts 

 are taken by molybdenum and tungsten trioxides, respectively. Among 

 minerals normal salts only are known. 



Powellite. 

 Belonesito. 

 Wulfenite. 

 Pateriuite. 



Group 1, 



CaMoO^. 

 MgMoO^. 

 PbMoO,. 



CoMoO,.(?) 



Tetragonal. 

 Tetragon al . 

 Tetragonal. 

 Tetragonal. 



Group 2. 

 a. Monoclinic section. 



Hiibnerite. 

 Wolframite. 

 Ferberite. 

 Raspitc. 



Scbeelite. 

 Cuproscbeelite. 

 Keinite. 

 Stolzite. 



MnWOj. 



(Mn,Fe)W04. 



FeW04. 



PbWO,. 



/S. Tetragonal section. 



CaWO^. 



(Ca,Cn)WO,. 



FeWO,. 



PbWO,. 



