THE CONSTITUENTS OF METEORITES 531 



iron-meteorites, as already indicated, are made up chiefly of 

 nickel-iron, with schreibersite, troilite, daubreelite and a few 

 other minerals occurring as accessories. 



Of the ironstone meteorites the largest quantity are of the 

 so-called pallasites, formed chiefly of chrysolite and nickel 

 iron. Nine falls of this group are known, having a weight of 1 742 

 kilograms. In the group known as siderophyrs, represented by 

 one fall (82 kilos), of meteoritic matter, bronzite and tridymite 

 are associated with the nickel-iron. In the group of mesosid- 

 erites (grahamites) represented by ten falls (483 kilos), of 

 meteoritic matter, the nickel-iron is accompanied by chrysolite, 

 bronzite, plagioclase, and augite. In the group lodranite, com- 

 posed of one fall with a weight of i kilo, chrysolite and bronzite 

 are associated with nickel-iron. 



Passing to the stone meteorites the following groups and 

 weights may be noted : 



A. Stones rich in calcium and magnesium and containing little or no 

 nickel-iron. 



1. Angrite. Chiefly augite. One fall, weight 0.4"^^. 



2. Eukrite. Augite and anorthite. Four falls, weight 91*^^. 



3. Shergottite. Augite and maskelynite. One fall, weight 5*^^. 



4. Howardite. Augite, anorthite, bronzite, and chrysolite. Ten falls, 

 weight 5''s. 



B. Stones rich in magnesia and containing little or no nickel-iron. 



1. Bustite. Diopside and bronzite. Two falls, weight 1.7"^^. 



2. Chassignite. Chiefly chrysolite. One fall, weight cg'^s. 



3. Chladnite. Chiefly orthorhombic pyroxene. Four falls, weight c^^. 



4. Amphoterite. Chiefly chrysolite and bronzite. Three falls, weight 40^^. 



C. Stones rich in magnesia and consisting essentially of chrysolite, 

 bronzite, nickel-iron, and iron sulphide. Here belong the great majority of 

 stone meteorites. 



A comparison of the constituents as above described with 

 those of the crust of the earth brings to view some interesting 

 similarities and contrasts. Under similarities may be noted the 

 fact that the elements of meteorites are the same as those of 

 the earth and that they unite according to the same chemical and 

 physical laws. No new element has been discovered in meteor- 

 ites and the chemical compounds of meteorites similar to those 

 of the earth agree even to the details of their crystal form. 



