Meteorites, and Volcanic Agency. 503 



the meteorites shows that they are the result of a gradual 

 tranquil crystallization, while others, on the contrary, are 

 composed of fragments, and are the product of disintegrating 

 forces. The majority are made up of minute flakes and 

 splinters and of rounded granules. 



Haidinger was the first who ventured to compare the porous 

 masses, made up of rock-dust, with the triturated and pul- 

 verized products of terrestrial volcanoes, and to term them 

 meteoric tuffs. The marked preponderance of this structural 

 character in meteorites shows that in the star-masses whence 

 they were derived a state of quiescence must have been of 

 much rarer occurrence than one of volcanic activity. 



In the tufaceous meteorites a characteristic feature presents 

 itself which throws considerable difficulties in the way of our 

 explanation, a phenomenon which is not observed in so marked 

 a degree in the tuffs of our volcanoes. It is the occurrence in 

 great abundance of minute rounded particles and spherules 

 which at once arrest the attention of the observer. They 

 characterize all tufaceous meteoric stones which, as already 

 stated, constitute the largest class of these bodies, and which 

 were termed by Rose " chondritic." 



These spherules present the following features, which suffice 

 to enable us to recognize their mode of formation * : — 



1. They are imbedded in a matrix consisting of fine or 

 coarse splinter-like particles. 



2. They are invariably larger than these particles. 



3. They are always distinct individuals, never merging into 

 each other or joined together. 



4. They are quite spherular when composed of a tough 

 mineral, and in other cases merely rounded in form. 



5. They consist sometimes of one mineral, sometimes of 

 several minerals, but always of the same material as the 

 matrix. 



6. The structure of the interior of a spherule is in no way 

 related to its external form. They are either fragments of a 

 crystal, or have fibrous structure (the fibres taking an oblique 

 direction towards the surface), or have irregularly barred 

 structure, or they are granular. 



These chondra bear no indications of having obtained their 

 spherular form by crystallization, and cannot be classed with 

 spherolitic obsidian or perlite, the spherules of orbicular diorite, 

 or the rounded concretions of calcite, aragonite, or marcasite. 



* Drawings of these spherules are given in the papers by Tschermak 

 on the Gopalpur meteorite {Sitzungsb. Ah. Wiss. Wien, lxv. 122) and on 

 the Orvinio meteorite (Sitzungsb. Ak. Wiss. Wien, lxx. Abth. i.), and that 

 by Von Drasche on the Lance stone {Miner alogische Mitt. 1875, i.). 



