Meteoric Stone %vliicli fell at the Mission Station of St. Mark's. 5 



taken place in the atmosphere at a period when the velocity of the 

 mass was still sufficient to allow of a crust, even an imperfect one, 

 being formed. Moreover, the original crust often terminates at such 

 places in a lumpy overlapping edge, so that its formation could not 

 have been complete when the splitting off took place, and this is an 

 additional proof that the meteorite cannot have suffered in the fall, 

 or afterwards. As for the statement that a piece of the meteorite 

 passed into other hands, this may be an error, due to its having been 

 noticed that one of the solid-angles was missing. On the other 

 hand, it is not impossible that two stones entered the atmosphere, 

 or that the fragment was found at some distance from the mass. 

 One cannot expect to find them close together, since the check to 

 the velocity of two pieces differing so much in weight does not occur 

 simultaneously. 



On breaking the stone it is found to be unusually tough ; further, 

 it can be seen at a glance that it belongs to the poorly represented 

 group of black chondritic meteorites. The fractured surface is rough, 

 of extraordinarily fine and even grain, and dark ashy grey; the 

 structure is firm and compact. Minute metallic flakes are uniformly 

 scattered over the whole, but they can be seen in part only with 

 the unaided eye. Some show such highly reflecting and seem- 

 ingly smooth surfaces that they might almost be taken for crystal 

 faces, but they are so very small that one cannot be certain of this. 

 Strange to say, even a strong lens fails to show any trace of iron 

 pyrites, although, judging from the high sulphur percentage, there 

 must be a good deal of it present. It may, however, take the form 

 of a fine dust, which w^ould account largely for the uniformly dark 

 colour. 



The chondrules seldom reach a diameter of 2 mm., and even at 

 half that size they are exceptional. The greater number are rounded, 

 and many are spherical ; sometimes, however, the shape is less 

 regular or the surfaces are broken. Some remain whole when the 

 stone is broken, and either stand out as hemi-spherules or fall out 

 and leave little dish-like hollows. They have a rough surface, and 

 are the same colour as the matrix. The greater number, however, 

 break, which shows that their adhesion to their surroundings is 

 stronger than their cohesion. When strongly magnified the broken 

 surfaces appear without exception flaky, and have a fatty lustre ; often 

 the nature of the structure can be made out, and this is, as a rule, 

 flaky, with a confused radiated arrangement, but occasionally fibrous, 

 with a regular, eccentric arrangement of the particles. At any rate the 

 microscopic examination only points to the presence of chondrules, 



