TITANIUM. 



429 



Brittle. Hardness from 6.0 to 6.5. Specific gravity from 4.18 to 4.40. Alone before the 

 blowpipe, it is not altered. It dissolves in borax, forming a hyacinth red bead. 



Varieties. Nigrine. This name is applied to the dark brown or black opaque mineral ; 

 while that of Rutile is given to the variety which has usually a blood-red colour. 



Composition. Rutile is composed of titanium 56 . 05, and oxygen 33 . 35 ; nigrine contains 

 oxide of titanium 84.00, oxide of iron 14.00, oxide of manganese 2.00. It has been sup- 

 posed by some that rutile also contains a portion of oxide of iron, and that both varieties are 

 titaniates of iron. The formula of rutile when pure, is TiOj. 



Geological Situation. This mineral usually occurs in granite and quartz rock. In this 

 State, it has also been found in primary limestone. 



localities. 



Essex County. According to Dr. Emmons, rutile occurs in the white limestone of this 

 and the adjoining county of Warren. 



Montgomery County. Mr. Mather has found minute crystals of this mineral in the calca- 

 reous spar near Spraker's basin. 



New- York County. Several forms of crystallized rutile have been found in the veins of 

 quartz, feldspar and mica, which traverse the primitive limestone 

 near Kingsbridge. Several varieties have been described by Dr. 

 Bruce, viz : Small, four-sided, prismatic, nearly acicular semi- 

 transparent crystals of a dark blood-red colour, in a granitic aggre- 

 gate of feldspar, bluish quartz and brown mica. Also the genicule- 

 ternaire of Haiiy, Fig. 512, consisting of two four-sided prisms, 

 so connected at their base as to form a jointed crystal ; dark red and 

 semi-transparent, s on s 126° 52'. 



Large amorphous masses of blood-red oxide of titanium were also 

 found on white feldspar with brown mica ; and the same mineral, 

 of a light red colour, with similar associates.* 



Orange County. Several localites of rutile occur in this county. 

 One of these is about a mile north of the village of Edenville, where 

 it is met with in limestone bowlders, associated with the variety of 

 hornblende called pargasite. 



Fig. 512. 



* Bruce. American Mineralogical Journal^ 235. 



