1917] Eakle: Minerals Associated with Crystalline Limestone 353 



Galena occurs in rather large cubes and also massive granular. 

 The specimens collected are associated with garnet dodecahedrons, 

 quartz, sphalerite, pyrite, and chalcopyrite. 



Sphalerite is quite black but has the characteristic resinous luster 

 and good cleavage. It occurs in the vesuvianite-garnet masses and 

 some of it contains small coatings of bright yellow greenockite. 



The copper minerals, bornite, chalcopyrite, tetrahedrite, and per- 

 haps chalcocite, have been found in grains and small granular masses 

 in the metamorphic zones of silicates. 



OXYDATION PEODUCTS 



Azurite and malachite occur as thin coatings and as stains in the 

 vesuvianite-garnet mass of rock. Cerussite and anglesite have both 

 been identified as earthy gray coatings on the galena. 



The two oxides of iron, limonite and hematite, are common in small 

 earthy masses and as stains. The weathered brucite limestone of the 

 Commercial Rock quarry has much yellow earthy limonite and deep 

 red hematite filling the cellular cavities left by the leached-out brucite. 

 The crystals and grains of pyrite imbedded in the calcite and even 

 in the pyroxene and other silicates have been largely altered into 

 limonite pseudomorphs, probably readily changed by the action of the 

 carbonated waters. 



White clay from the orthoclase and chlorite from the epidote, 

 augite, hornblende, and other silicates are natural alteration products. 



