ALUMINA. 



319 



AUTOMOLITE. 



|Fiom the Greek au-ojAoXof, a d: -iter ; on account of the presence of the oxide of zinc.] 

 Automolitc. Philiips and T/wmsmi. — Gah '■ Chtvdand anil D-iidant. — SpmcWc.Zinciaic. Hauv. — Oc- 



■Ao?«so«. — L.'a!i '■ Chtvdand a.nil D'lidant. — Spindle; Zinci&re. //auj/. 

 tail dial Corundu.ii. Juvicson. — Octaedrischer Korund. Mohs. 



rig. 2G5. 



Des^'ition. Colour muddy dark blue, passing into blackish 

 green. Streak white. It occurs regularly crystallized. Primary 

 iorm a regular octahedron, Fig. 265. Cleavage parallel with the 

 primary faces. Fracture conchoidal. E.xternal lustre pearly, in- 

 clining to semi-metallic ; internally, shining and resinous. Opaque, 

 or faintly translucent on the edges. Hardness 8.0. Specific gravi- 

 ty from 4.23 to 4.70. Before the blowpipe it is unalterable alone, 

 and nearly so with salt of phosphorus or borax. When the mineral 

 is subjected to heat with caustic potash, and treated with an acid 

 the alumina is precipitated by ammonia. From this solution, oxide of zinc is again precipi- 

 tated, when it is saturated by an acid. 



In its crystalline form, automolite resembles spinelle ; but it differs in being heavier, in 

 having a different colour, and especially in containing a large proportion of o.\ide of zinc. 



Composition. A specimen from the United States — Alumina 57.09, silica 1.22, oxide of 

 zinc 34.80, magnesia 2.22, protoxide of iron 4.55 (AbicJi). 



Geological Situation. It is usually found in primitive rocks. 



LOCALITIES. 



St. Lawrence County. Automolite has been credited to the village of Rossie, where it 

 was said to have been found in minute octahedrons, in calcareous spar.* I am inclined to be- 

 lieve, however, that the mineral here referred to is common spinelle. It is introduced among 

 the New- York minerals on the above authority, and for the purpose of directing the inquiries 

 of our mineralogists to the subject. 



According to Shcpard, it occurs at Haddam in Connecticut, where it is associated with 

 chrysoberyl, garnet and columbite, in granite. 



* Finch. AjTierican Journal of Science. XIX. 220. 



