L06 



NEW YORK STATE MUSEUM 



Subsilicates 



The minerals here included are probably either metasilicates 

 or orthosilicates. which, for lack of definite knowledge regarding 

 their constitution, have been classed by Dana under this head. 



Humite group 



This group includes the species chondrodite. humite and clino- 

 huniite. They are basic fluosilicates of magnesium and are 

 closely related chemically. They occur in crystals which are 

 extremely complicated (chondrodite and clinohumite are mono- 

 clinic, and humite is orthorhombic). Clinohumite and chondro- 

 dite occur in compact masses and disseminated grains. A vit- 

 reous to resinous luster is common to the group and the general 

 color is red, brownish red, brown to yellow. 



The humite group occur mainly in ejected masses of limestone 

 and are associated with chrysolite, biotite. pyroxene, magnetite, 

 spinel, etc. The minerals of the humite group are all found at 

 the Tilly Foster mine, Putnam co. X. Y. 



Calamin H 2 ZnSiO : , 

 Calamin is a basic zinc silicate containing 67.5^ zinc oxid, 

 25$ silica and 7.5$ water. 



The crystals are orthorhombic-hemimorphic, usually tabular 

 parallel to the brachypinacoid (fig. 229) and are frequently 

 joined in radiated groups forming a rounded 

 notched ridge or cockscomb (pi. 32 x ). Granular. 

 ( stalactitic and botryoidal masses are also found. 



The luster is vitreous to pearly. Isolated crys- 

 tals are occasionally colorless and transparent: 

 in general the color is white, more rarely delicate 

 shades of blue or green and yellow to brown in 

 the massive varieties. 



Calamin usually accompanies smithsonite in 

 veins and cavities in stratified calcareous rocks associated with 

 the sulfids of zinc, iron and lead. It is mined in considerable 

 amounts in Silesia and Rhenish Germany. In the United States 

 it occurs extensively at Granby Mo.; also at Sterling Hill X. J., 

 Bethlehem Pa. and in Virginia. Pennsylvania. Utah and Montana. 



As an ore of zinc it is valued as being comparatively free from 

 volatile impurities. 



