Aasfr(difey< jroni Western Victoria, 363 



A/)/)earafice of Aifstralife. 

 General cliaraoteis. — Tlie speciinen is sliaped somewhat like a 

 pine-seed, being elliptical in outline, flat above, convex below, and 

 tapering at its edge to a thin flange, which is flat at the extremities 

 of the specimen, and curved back on the middle part of the upper 

 surface. The flange has l)een slightly chipped near each extremity. 

 The colour of the australite ranges from light yellow in the thin 

 flange, thvougli bottle-green to black, but even the thickest part is 

 translucent. 



Fhif (ir upper surface. 



Examiifed under the microscope Avith a 2-inch objective, numer- 

 ous small pits of hemispherical shape are noticed on the middle 

 part of the upper surface. Near the flange these pass into semi- 

 cylindrical grooves, which are recurved at the junction with the 

 flange. The recurving is in opposite directions on opposite sides 

 of the central part of the flange. Near the extremities of the longer 

 axis of the specimen tlie grooves run out into the flange parallel to 

 the longer axis of the specimen. This recurving of the grooves 

 alluded to above is what would be expected to occur if they were" 

 formed while the glass was still plastic and rotating about an axis at 

 right angles to the flat or upper side, while the turning upwards of 

 the central part of the flange might be expected to occur in a plastic 

 body as a result of resistance from the air, Avhile the body was mov- 

 ing in the direction of the assumed axis of rotation. 



Convex or lower surface. 



Pits and grooves are also noticed on this surface of the speci- 

 men. In the middle of the specimen they are hemispherical, at 

 the margins of the central part they become semi-elliptical to semi- 

 cylindrical, and in the flange, especially at the extremities of the 

 longer axis, they are drawn out to linear grooves. 



Examination of interior of Australite. 



For this purpose the australite Avas immersed in water in a 

 watch glass, and examined under the microscope. 



The specimen shows no sign of crystals or incipient crystals; 

 it is completely glassy. In polarised light the central parts are 

 completely isotropic, but the marginal parts, especially the thin 

 part of the flange, exhibit grey to Avhite polarization colours, in- 

 dicating the existence of a state of sti-ain in the glass of the mar- 

 gin and flange of the australite. 



