18 ROGERS— NOTES ON PSEUDOMORPHS, [February 4, 



Pseudomorphs of copper after cuprite from Cornwall have been 

 described by Miers;^ copper after azurite from New Mexico by 

 Yeates ;- and copper after aragonite from Bolivia by Forbes.^ 



3. Chalcedony after Calcite. — Guanajuato, Mexico. Obtained 

 from the Foote Mineral GDmpany. An excellent specimen of this 

 pseudomorph consists of pale brown chalcedony in the form of hol- 

 low doubly terminated scalenohedrons (2131) of calcite about i cm. 

 in length. 



4. Hematite after Marcasite. — Lake Co., California. Collected 

 by Mr. H. E. Kramm from the Baker mine, six miles from Lower 

 Lake on the road to Knoxville. The specimen consists of small 

 encrusting crystals giving a red streak. They have the same form 

 as unaltered marcasite crystals from the same mine. 



5. Limonite after ChaJcopyritc. — Granby, Missouri. Small tet- 

 rahedra (2 mm.) of dark brown limonite on a specimen of dolomite, 

 calamine, and smithsonite have been produced by the alteration of 

 chalcopyrite. The author found similar pseudomorphs at Galena, 

 Kansas, but it is a rare kind of pseudomorph. 



6. Limonite after Cerussite. — Burke, Idaho. Collected by Mr. 

 H. F. Humphrey at the Bunker Hill mine. At this mine cerussite 

 is a prominent gossan mineral. Several specimens show prismatic 

 crystal aggregates of cerussite with a coating of limonite. Other 

 specimens show limonite of a form exactly similar to the cerussite 

 and are undoubtedly pseudomorphs. 



7. Wad after Calcite. — Echo Mine near Mojave, California. 

 Collected by Mr. H. W. Young. Cavities in a quartz matrix with 

 the shape of calcite scalenohedrons are occupied by a soft black 

 mineral answering the tests of wad. These are not direct substitu- 

 tion pseudomorphs but probably represent quartz encrustation 

 pseudomorphs after calcite in which the calcite was dissolved out 

 and then the cavities filled with wad. 



8. Calcite paramorph after Aragonite. — Patterson Pass, east of 

 Livermore, California. A travertine deposit in buff Miocene sand- 

 stone consists of a banded, coarsely fibrous aragonite of an amber 



^ Min. Mag., Vol. II., p. 266, 1897. 



'Am. Jour. Sci., Vol. 38, p. 405, 1889. 



^ Quar. Jour. Geol. Soc, Vol. 17, p. 45, 1861. 



