130 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



7. CORUNDOPHILITE. 



The present mineral has not yet been fully analyzed. An imperfect examination 

 made of a few grains of it found along with the sapphire of Buncombe, North Carolina, 

 lead to the conclusion that, like ottrelite, it is a silicate of alumina and protoxide of 

 iron, but with little lime and magnesia. Des Cloizeaux has described it as one of the 

 micaceous minerals, but it rather appears to belong to the cliuochlore group. Its 

 crystallization is near to mica and its hardness is between 2 and 3. Its laminse 

 are inelastic and almost brittle. In color and in the arrangement of its particles, 

 even when giving rise to a slate, as it often does, it does not resemble the well-known 

 mineral chlorite. It is of all others the most abundant gangue mineral of the purer 

 varieties of both emery and magnetite. 



8. Indianite. 



Exterior to its vein, on its eastern side and a few feet within the talcose slate, 

 at a place on the South Mountain near the smaller Westfleld Eiver, runs a layer or 

 stratum from 6 inches to 2 feet in thickness, called by the workmen "//;e fringe rock.''^ 

 It consists of a soft, columnar mineral, but it is difficult to say whether it is chlorite or 

 corundophilite, or whether it may not be a mechanical mixture of the two. The 

 columns or fibers, if such they can be called, are perpendicular to the sides of the 

 vein and are made up of superimposed scales of the mineral. The columns have been 

 rendered tortuous and wavy by lateral pressure. Through the middle of this stratum 

 runs, with occasional interruptions, a vein of indianite varying from 2 to 10 inches in 

 thickness. The mineral is massive, finely granular, of a yellowish color, and contains 

 grains of corundum, whereby it is easily capable of scratching quartz. 



9. Tourmaline. 



This is also a highly prevalent mineral throughout the entire course of the vein, 

 though perhaps most abundant on the North Mountain. It is more frequent near the 

 sides of the vein, though at some places it is interlaminated through its entire mass, 

 showing itself on the cleavage surfaces. The crystals are often several inches long 

 and from one-fifth to three-fourths of au inch in diameter, being arranged in fascic- 

 ular and radiatiug groups with their longer axes conforming to the stratification of 

 the rock. The crystals are usually six-sided prisms with smooth surfaces, but always 

 lacking regular terminations. Their color is brownish black. 



10. Epidote. 



Though not abundant, it is nevertheless frequently observed, especially in the 

 vein on both sides of the smaller Westfield River, near the mill. It is in light 

 yellowish-green crystals, 1 or 2 inches long by one-eighth to one-fifth of an inch in 

 diameter, the crystals being arranged parallel to the lamination of the vein and being 

 often associated with grayish scales of margarite, ottrelite, and with emery. A beau- 

 tiful radiated pistachio-green epidote, accompanied by diaspore, has also been observed 

 in the same vicinity coatiug the cross joints of the vein rock. 



