TITANIUM. 



433 



SPHENE. 



[From the Greek ff^vjv, a iccdge ; probably in reference to the form of some of its crystals.] 



Titanc SUioco-Calcairc. Ili/.nj. — Silico-Calcaroous 0\idi' of Titanium. Clrnvehimh — Splicnc. Phillips, Thomsmi, 

 SkcparJ ami Bcndniil. — Ilcmiprismatic- Titanium-Ore. Jameson. — Prismatischcs Titan-Erz, Malis. 



^'^■^"'' Fig. 520. Description. Colour yellow, brown, green and 



grey, usually dull. Streak greyish white. It occurs 

 regularly crystallized ; also massive, in granular and 

 lamellar distinct concretions. Primary form an 

 oblique rhombic prism. Fig. .519. M on M' 1.33° 

 30'; P on M 121° 50' {PhUUps and Beudant). 

 Fig. 520. M on M' 76° 2' ; M or M' on P 93° V 

 (G. Rose and Thomson). Cleavage parallel to the 

 faces of the primary prism, but not distinct. Fracture 

 imperfect conchoidal. Lustre adamantine, .some- 

 times inclining to resinous. Varies from transparent to opaque. Hardness from 5.0 to 5.5. 

 Specific gravity from 3.49 to 3.60. Before the blowpipe, it fuses with difficulty into a dark 

 coloured enamel ; with borax, it affords a yellowish green diaphanous glass. It is soluble in 

 heated muriatic or nitric acid, leaving a siliceous residue. By boiling, the titanic acid is pre- 

 cipitated. 



Composition. Oxide of titanium 33.00, silica .35.00, lime 33.00, trace of manganese 

 {Klaproth). Titanic acid 48.00, silica 33.00, lime 19.00 (Rose). The latter results, it 

 will be observed, differ considerably from those obtained by Klaproth and Cordicr. 



Geological Situation. This mineral occurs in small nodules or crystals in granite, gneiss, 

 and primitive limestone. In this State, it is most frequently found in the latter rock. 



EssE.x County. Sphene was first noticed as a New- York mineral, in the vicinity of Ticon- 

 deroga, by the late Col. Gibbs.* The crystals were described as having a yellowish grey 

 colour, and the form of rhomboidal prisms terminated by dihedral summits. They were 

 imbedded in an aggregate of white granular and lamellar feldspar. 



Dr. Bruce has also described, as from the vicinity of Lake George, probably froiu Kogcrs' 

 rock, large clove-brown crystals in form similar to that of Fig. 521, imbedded in a rock com- 

 posed of hornblende, feldspar and foliated graphite. 



At Rogers' rock, crystallized sphene is very abundant, and is associated with pyroxene and 

 graphite. The crystals arc of various sizes, have a brown colour, and exhibit the forms 

 represented in Figs. 522, 523 and .524. M or M' on a 139° 30'; P on c, 158° 18'; c on d, 

 146° 44' ; c on e 145° 18'; c, on o 136° 50' {Phillips). 



MiN. — Part II. 



* Amrrtcan Mincrahgical Journal, 239. 



55 



