Australian Museum Journal Mineralogical notes. No. XI. Diamond

Shortform:
Anderson, 1922, Rec. Aust. Mus. 13(5): 201–212
Author(s):
Anderson, C.
Year published:
1922
Title:
Mineralogical notes. No. XI. Diamond
Serial title:
Records of the Australian Museum
Volume:
13
Issue:
5
Start page:
201
End page:
212
DOI:
10.3853/j.0067-1975.13.1922.873
Language:
English
Plates:
plates xxxviii–xli
Date published:
15 March 1922
Cover date:
15 March 1922
ISSN:
0067-1975
CODEN:
RAUMAJ
Publisher:
The Australian Museum
Place published:
Sydney, Australia
Subjects:
MINERALOGY; GEM STONES
Digitized:
08 January 2009
Available online:
06 March 2009
Reference number:
873
EndNote package:
EndNote file
Title page:
Title page (86kb PDF)
Complete work:
Complete work (1337kb PDF)

Abstract

An interesting diamond crystal from this field was lent by Mr. D. A. Porter for measurement and description. The diamonds at this locality are found in deposits of sand and gravel, probably of Pliocene age, underlying the basalt capping of a number of isolated hills; they are accompanied by stream tin and a little gold.

The crystal weighs 0.0443 grams. It is colourless, and consists of a hexakis-octahedron with indices near (111), twinned on an octahedral face (spinel law), and flattened parallel to the twin plane to form a triangular plate; diamonds of this shape are known at Amsterdam as naadsteenen (suture stones). Only six faces of each half of the twin are developed, forming a very low pyramid with curved edges and planes, each face striated in lines running roughly parallel to its intersections with an octahedral face, but towards the periphery the striations curve in conformity with the crystal edges and gradually disappear. A few small triangular depressions appear near the apex, the corners of the pits, as is usual in natural etch pits of the diamond, being directed towards an adjacent octahedral edge.