191^] Certain Mineral Resources 21 



rocks, or in the serpentines which have resulted from the alter- 

 ation of these rocks. In the iN^orth Carolina peridotites, chro- 

 mite occurs more commonly in grains or crystals, and also in 

 embedded masses, near the boundary of the lenticular bodies of 

 these rocks. 



The mineral does not occur in well-defined veins, but is often 

 in masses or pockets which apparently have no relation what- 

 ever to one another. 



But few authors writing upon the occurrence of chromite 

 have described the relsrtion of the chromite deposit to the rocks 

 in which it is found. One or two have mentioned the chromite 

 as being found near the eastern boundary or at the northern 

 border of the serpentine belt ; but in no case has the writer been 

 able to find any definite description. The large deposits of chro- 

 mite in North Carolina occur in the peridotite rock, and near the 

 contact of this rock with the inclosing gneiss ; and where there is 

 but a small amount of the chromite, either in pockets or in 

 grains or crystals, these are more abundant near the contact and 

 diminish in number toward the center of the mass of peridotite. 



Mention has been made above of deposits of corundum that 

 occur in peridotite rocks, but where we find these large deposits 

 there is a scarcity of chromite, and where the larger deposits of 

 chromite occur there has been little or no corundum found. 



Crystallized chromite has been found only in small, isolated 

 crystals scattered through the peridotite, or where these crystals 

 have been concentrated in alluvial deposits. The masses of 

 chromite show little or no crystalline structure. 



The constant occurrence of the chromite in rounded masses 

 of varying proportions near the contact of the peridotite, with 

 the gneiss, and its occurrence in the fresh as well as the altered 

 peridotite indicate that the chromite has been held in solution in 

 the molten mass of the peridotite when it was intruded into the 

 country rock, and that it separated out among the first minerals 

 as this mass began to cool. 



The peridotite (dunite) magma, holding in solution the 

 chemical elements of the different minerals, would be like a 

 saturated liquid, and as it began to cool the minerals would 



