I posted this the other day on another thread...
The Mineral Resources of New South Wales by Edward F Pittman 1901
page 395
The Mittagong Diamond Mine
The late Mr C. S Wilkinson Geological Surveyor in charge reported in 1890 on the occurrence of diamonds in connection with a supposed volcanic pipe. The following is an extract from his report:- the diamond mine so called is situated about seven miles south easterly from Mittagong on a creek flowing into the Nepean river. Here there is a small isolated patch about 300 feet in diameter of fine and coarse pebble drift. The remnant of the bed of a stream which in the Tertiary period flowed across the Hawkesbury Sandstone formation. It was probably the old channel of the Nepean River before it had been diverted and eroded to form the present valley. The drift rests upon a stiff clay, which forms the surface of the pipe- dyke mass of volcanic breccia, intruding the Hawkesbury formation, For several years it has been more or less worked for gold, when, during the process of washing , diamonds were discovered. It is said they were obtained chiefly
from the stiff clay at the bottom of the drift. Mr Southey who with Mr Dunstan holds the ground informed me that thirty three diamonds had been found the largest weighing 2 carats I saw some of these diamonds which were chiefly well formed octahedra of the first water the other being a pale yellow colour. If systematic search were made here doubtless many more would be found. Whether the diamonds have been transported with the old tertiary drift from some formation higher up the Nepean valley or have been derived from the volcanic breccias on which the drift rests or from the Hawkesbury sandstones and shales where they have been altered by contact with the intrusive volcanic rock has not been definitely ascertained but it is probable that the breccias is their source. The breccia contains small fragments of coal and in some respects resembles the diamondiferous rock of the Kimberley field in South Africa
It may be mentioned that since Mr Wilkinsons report was written as attempt as made to prospect the breccia by means of a shaft. After sinking for about sixty feet. however a strong body of water was met with and the mine was abandoned.
A limited number of diamonds have been found, principally from a location
known as Digger's Creek, seven miles south east fro Mittagong. They were
found, with fine alluvial gold, in a patch of old gravels overlying a
volcanic formation. A few stones were also found in gravels near Kangaloon.
A general search in the Wingecarribee River had little success although some
sapphire fragments of fair size were recovered' Source: Hannan, F.
(ed)Gold , Minerals & Gem stones Localities of NSW.
:Y:
