Meteoric Stone icJiicli fell at the Mission Station of St. Mark's. 11 



to a porphyritic-like structure. After these, but in much smaller 

 number, come the chondrules having a more or less regular, eccen- 

 tric, radiated structure, in which the individuals never, as so often 

 happens, dwindle to the fineness of fibres. With this kind of 

 structure especially there occur what appear to be fragments. But 

 that they are really such seems to me very doubtful and, judging 

 from the whole nature of their occurrence, I am more inclined to 

 think that they are independent, radiating bundles of enstatite 

 prisms which only by chance resemble the cross-section of a 

 spherule. Enstatite chondrules showing other structures occur only 

 here and there. For instance, there are some made up of a few 

 broad crystals (Plate III., Fig. 4). Others, again, are of fibres, with 

 abundant interspersed ores arranged so as to form a lattice or 

 fan-like structure. When the individuals are cut at right angles to 

 the vertical axis, which can be ascertained from the cleavage traces, 

 they seem as if they were formed of small isometric grains of about 

 equal size, and resemble the facetted eye of an insect. 



Olivine is more abundant in the matrix than in the chondrules, 

 and in both its distribution is quite irregular. It occurs, as a rule, in 

 the form of more or less isometric grains, of which occasionally 

 several of the same kind lie close together, so that they may be 

 taken for parts of a larger crystal. Definite crystal faces may occur 

 where an isolated individual lies in iron chondrules or in the larger 

 nickel-iron particles.* The olivine is, as a rule, quite free from cracks, 

 and contains, besides opaque particles, little gas-bubbles, mostly 

 in rows or collected in groups, and colourless glass with or without 

 bubbles. The two latter inclusions appear to be absent from the 

 enstatite. The rare chondrules composed only of olivine are poly- 

 somatic and granular. Only here and there does one see mixed 

 chondrules in which the largely predominating enstatite is accom- 

 panied by a few olivine grains. 



The analysis for the chemical composition was conducted as 

 follows : First, a portion of the pulverised stone was digested for 

 some time with dilute hydrochloric acid, and the silica of the 

 soluble silicates obtained by treating the residue with caustic soda 

 and caustic potash solutions. The determination of sulphur, carbon, 



* In very similar cases one may observe in the matrix clear, sharply defined 

 particles, occasionally hexagonal. These show, between crossed nicols, when the 

 stage is rotated, a quick alternation of dark and light, have weak double re- 

 fraction and low relief. Their optical character is uniaxial and positive. All this 

 points to quartz, which the analysis, with its silica excess, also confirms. The 

 meteorite is thus allied to certain grahamites and to terrestrial basalts, in which 

 similar phenomena are observed. — C. K. 



