526 STUDIES FOR STUDENTS 



The meteorites from which ferric chloride exudes disinte- 

 grate with especial rapidity. Such meteorites are often known 

 as "sweating" meteorites. The "sweating" is rarely noted in 

 ironstone or stone meteorites, but the small percentage of chlo- 

 rine found in the analysis of many of these meteorites is usually 

 referred to lawrencite. Some authorities hold that the substance 

 is not an original constituent of any meteorite, but is wholly of 

 terrestrial origin. This is not the general opinion however. 



Ferrous chloride has been noted among the sublimation 

 products at Vesuvius and is reported as having been found in 

 the terrestrial nickel-iron of Ovifak. 



Magnetite. — Several stone or ironstone meteorites have been 

 found to contain black, magnetic grains which dissolve in hydro- 

 chloric acid without effervescence to form a yellow solution. 



In the meteorites of Shergotty and Dona Inez these are suf- 

 ficiently abundant to form an essential constituent. They con- 

 stitute 4.57 per cent, of the Shergotty meteorite. Similar grains 

 occur as inclusions in maskelynite, pyroxene, and chrysolite in 

 the above and other meteorites. They are regarded as mag- 

 netite. 



No well marked crystals of meteoritic magnetite have as yet 

 been described. 



Magnetite has been reported as a constituent of several iron 

 meteorites though only one analysis has been made, that of 

 Meunier of magnetite from the crust of one of the Toluca irons. 

 The composition of this agreed with that of terrestrial magnet- 

 ite. Several other iron meteorites show magnetite in their 

 crust. Here, however, the magnetite may have originated from 

 the oxidation of the iron of the mass since its arrival upon the 

 earth. : _ 



Magnetic spherules have been dredged up from ocean depths, 

 which Murray and Renard regard as particles of meteoric iron 

 oxidized to magnetite since their arrival upon the earth. 



^Oldhamite. — This is a simple calcium sulphide with the for- 

 mula Ca Sg. Grains of it were found by Maskelyne embedded 

 in the enstatite or augite of the Bustee meteorite. It: is light 



