440 Prof. Maskclyne and Dr. Lang's Mineralogical Notes. 



compact homogeneous granular mass; others exhibit in their 

 sharpest features either the barred, the fanned, or the mottled 

 minerals, of which I shall give descriptions in a future article*. 

 The iron, again, may be seen in every condition as irregularly 

 shaped grains and particles, or as microscopic dust; or it 

 may be found entangled in or entangling sponge-like masses 

 of meteoric pyrites ; while either of these bodies may be seen in 

 turn penetrating the spherules, or containing a spherule com- 

 pletely enclosed in them./ Or, again, we may find one of those 

 curious veins of metal or of meteoric pyrites, or of these asso- 

 ciated with other minerals highly charged with oxide of iron, 

 which betray a stage in the history of the aerolitic rock subse- 

 quent to that in which the mass had become compacted as we 

 now see it, a stage during which it underwent a subsequent split- 

 ting along a direction now indicated by the narrow vein that 

 fills the fissure, and which, running through the spherules, has 

 divided them and " heaved" them. Such a vein brings evidence 

 to prove, by the non- continuity of the outlines of the spherules 

 on either side of it, that there have been stages in the progress 

 of the slag-like mass from the first origin of the spherule — in 

 perhaps a seething lake of mixed and molten metals on which a 

 rare oxygenous atmosphere was acting and fermenting out as it 

 were the more oxidizable elements — to the final state of compact 

 continuity in which the spherules are found agglutinated together 

 or imbedded in a magma of mineral. ,/ 



Parnallee is in these respects more singular, and it presents 

 also a more beautiful object in the microscope than do even Bor- 

 kut, Mezo-Madaras, Bremevorde, Tabor, or Seres, 



Its specific gravity = 3*41. 



12. Durala. Plate IX. 



The aerolite which fell at Durala on February 18, 1815, was 

 presented, in the state in which it fell, to the East India Com- 

 pany. After remaining in the library of the East India House 

 till the change of government took place, it was presented in 

 1861 to the British Museum by the Secretary of State for India 

 in Council. The following circumstances attending its fall are 

 taken from the Report of the British Association for 1850. 



Extracts from a letter from Captain G. Bird, first assistant in 

 the Political Department, to Major-General Sir D. Ochterlony, 

 Bart., K.G.C.B., to Major Penington :— 



* In a subsequent Number I propose giving a more systematic and de- 

 tailed account of the appearances presented generally by the different varie- 

 ties of spherule, and of the magma that contains them, in chondritic 

 aerolites. 



