1870.] 



Mineral Constituents of Meteorites. 



149 



The meteorite consists for the most part of the mineral enstatite ; at one 

 end, however, was imbedded a number of small chestnut-brown spheruies, 

 in which again a lens enabled me to detect minute octahedral crystals, 

 having the lustre and colour of gold. 



These two minerals seem scarcely to have been affected by the heat that 

 fused the silicates which surround and encrust them. 



IV. Sulphide of Calcium (Oldhamite). 



This mineral occurs in the Busti aerolite, and sparsely in that which fell 

 at Bishopsville, imbedded in augite, or enstatite, or both of them. It 

 has a pale chestnut-brown colour, and forms small, nearly round spherules, 

 whose outer surface is generally coated with calcium sulphate. It cleaves 

 with equal facility in three directions, which give normal angles, averaging 

 89° 57', and are no doubt really 90°. Its system, therefore, is cubic; 

 indeed in polarized light it is seen to be devoid of double refraction. Its 

 specific gravity is 2*58, and its hardness 3*5 to 4. With boiling water it 

 yields calcium polysulphides, and in acids it easily dissolves with evolu- 

 tion of hydrogen sulphide. Chemical analyses indicated the following as 

 its composition : — 



I. II. 



Oldhamite / Calcium monosulphide 89*369 90*244 



\ Magnesium monosulphide 3*246 3 264 



Gypsum 3-951 4*189 



Calcium carbonate 3*434 



Troilite 2*303 



100*000 100*000 



The presence of such a sulphide in a meteorite shows that the condi- 

 tions under which the ingredients of the rock took their present form are 

 unlike those met with in our globe. Water and oxygen must have alike 

 been absent. The existence of iron in a state of minute division, as often 

 found in meteorites, leads to a similar conclusion. But if we bear in mind 

 the conditions necessary for the formation of pure calcium sulphide, the 

 evidence imported into this inquiry by the Busti aerolite seems further 

 to point to the presence of a reducing agent during the formation of its 

 constituent minerals ; whilst the crystalline structure of the Oldhamite 

 and of the Osbornite must certainly have been the result of fusion at an 

 enormous temperature. The detection of hydrogen in meteoric iron by 

 Professor Graham tends to confirm the probability of the presence of such 

 a reducing agent. 



V. Osbornite. 



The golden-yellow microscopic octahedra imbedded in the Oldhamite 

 were furnished by the analyses of that mineral to the amount of only 

 0*0028 gramme, and though upwards of 150 in number, were capable of 

 being measured by the goniometer. 



This microscopic mineral I wish to name Osbornite, in honour of Mr. 



m 2 



