158 THE KORALEIGH STONY METEORITE 
MINERALOGY 
A thin section of the aerolite revealed that it is principally 
crystalline, with a granular to micro-porphyritic texture. Con- 
siderable staining by secondary hydrous oxides of iron has taken 
place right through the specimen. 
The greater portion of the silicate minerals consists of granular 
olivine and crystals of bronzite with 2V approximately 90°. Oceca- 
sional chondrules of the barred monosomatiec variety and of the 
radiating and granular polysomatic variety are present. Twenty 
chondrules occurred in one thin section, measuring { in. x @ in. 
The types of chondrules are similar to those occurring in the Bond 
Springs stony meteorite from Central Australia (Baker and 
Edwards, 1941), though they are not as numerous. The largest 
chondrule observed was the detached one measuring 7 mm. across; 
the smallest measured approximately 1 mm. in diameter. 
Metal and iron sulphide grains are seattered throughout the 
section as small patches of irregular shape. They are frequently 
enveloped by limonite, the metal more so than the sulphide 
minerals. 
The volume percentages of the silicate minerals and of the metal 
+ sulphide were determined from 14 traverses, taken at 1 mm. 
intervals across a thin section, by means of an integrating machine. 
This resulted in a value of 97% for the metal + sulphide, with 
the sulphide mineral considerably in excess of the metallic iron. 
This percentage value is lower than that for the Bond Springs 
aerolite (12% by volume), partly because of considerable altera- 
tion by weathering of the iron in the Koraleigh aerolite. 
The silicate minerals and small amounts of glassy material 
comprise the remaining 903% by volume of the aerolite. They 
have suffered slight decomposition, occasional alteration products 
(probably serpentine and iron oxide dust) occurring along cracks 
in some of the olivine crystals. They are invariably stained by 
thin films of secondary iron oxides derived from the metallic 
constituents. 
Rare interstitial areas with low birefringence and vague twin 
lamellae are probably plagioclase felspar. Some of the clear areas 
between the grains and erystals of olivine and bronzite are 
uniaxial, negative, and probably correspond to the sodium-calcium 
phosphate mineral, merrillite, the presence of which was estab- 
lished by Stillwell in the Caroline stony meteorite. 
Other rare interstitial areas which are clear and principally 
isotropic, represent maskelynite or devitrified glass. As in the 
Caroline stony meteorite, minute particles of reddish-brown colour 
and isotropic character, included in the olivine and pyroxene 
