11^ MINERALS OF MARYLAND. 



not yet been analyzed, tt appears to be either a hydroxide of 

 chrome or a hjdrosilicate. The oxides and acids of chrome 

 enter largely into the composition of the colouring matter of 

 the serpentine and its associated magnesian minerals, and with 

 iron and magnesia produce their inniunerable varieties of 

 beautiful shades and tints. 



Pyritous copper and magnetic oxide of iron occur at one 

 spot, iu the Cooptown district, associated with ferroxide of 

 chrome and talc in serpentine. 



Sulphuret of antimony has recently been found in the ser- 

 pentine formation of 'Soldier's Delight.' 



It has been already remarked that the mica-slates most 

 abounds in the north-western part of the primary region. It 

 passes by imperceptible gradations into talcose slates, and pri- 

 mary argillites, which are remarkable for their great uniformity 

 and for the scarcity of mineral species in that part of this range 

 within the limits of Maryland. 



Quartz, having a greasy lustre, is either disseminated in it, 

 or forms veins, which are sometimes of considerable thickness 

 and extent, and it contains no other mineral that has come to 

 my knowledge, except sulphuret of w■o?^. In one place the 

 sulphuret of iron has existed in abundance, but the greater 

 part of it has become oxidated, and the rock presents precisely 

 the appearance and is in the same relative geological position 

 as part of the gold region of North Carolina. Of late years 

 this metal has been traced from North Carolina, through 

 Virginia, almost to our borders, and there is some reason io fear 

 that it will eventually be found in this state ; an evil which it is 

 to be hoped will be averted, because of the tendency that it 

 would inevitably produce of drawing off the attention of the 

 people from more useful and more profitable pursuits. 



The third division we proposed to extend from Parr's 

 spring ridge to the foot of the Catoctin mountains, being the 

 basin of the Monococy river. Parr's ridge has usually been 

 considered about the line of separation between the primary 

 and older transition formations, but in fact there is no line of 

 separation. The mica slate absolutely alternates with and 

 passes into the primary argillite, which itself by imperceptible 

 changes passes into both roofing slate and compact blue lime- 

 stone, decidedly transition. That portion of this division east 



