The study of opal deposits in Australia
July 10, 2005
The study in Australia was carried out using GROT 10 and GROT 11 ground penetrating radars. Lightning Ridge is a large opal field, which is situated around the town of the same name, as well as a number of peripheral opal fields, some of which are worked out. The workings at a number of fields are carried out and a large amount of opal has been won.
The objectives of the study were:
To trace opal mineralization in terms of the area and depth within the boundaries specified by the customer.
Ecology. To reduce harm to the environment during the exploration of natural resources: to minimize the number of exploration drillings, and as a result, to reduce the degree of anthropogenic disturbance to the unique natural Australian landscape, to save the native fauna due to the lower probability of domestic and wild animals falling into the drilling holes. To reduce the amount of water and fuel consumption and emission of harmful gases during the exploration for opals (opal prospecting).
To improve economic efficiency and intelligence of opal mining through the use of a new GPR technology.
The field workings was carried out basing on the method of GPR scanning of tracks at four test and six research ranges, located in different parts of Lightning Ridge.
On the photograph there is a typical section of rocks enclosing an opal mineralization. There is a low-grade slope of the tectonic disturbance containing the richest opal-bearing lenses.
The lithologically heterogeneous layers due to their contrasting physical and mechanical properties and different moistness are clearly distinguishable on the radargrams. The thin seams and separate geological bodies (nodules, cavities, etc.) appear on the radargram as local anomalies.
The GPR scanning of the tracks allowed us promptly identifying and tracing to the depth the major and minor faults, which determine the spatial position of potential opal-bearing zones, as well as determining the depth of the most contrasting subsurface layers.
The radargram obtained by means of GPR scanning of the track along the upper edge of a mine reveals:
a) the lithological heterogeneous layers in conventional color palette ;
b) the tectonic disturbances in the form of inclined lines;
c) the outfall of the horizontal mine workings.
Don Yakoumelos, an independent world-class expert in mining, processing and sales for opals, sapphires, rubies and other precious minerals, who was a consultant during the whole expedition said:
"What I saw made a great impression on me, especially the quality and high efficiency of using GPR. Thanks to GPR an opal mining becomes more cost - effective and more environmentally friendly due to significant reduction in costly drilling, which is so harmful to the environment."
The outcome: the GROT georadars revealed the exact position of opals in the studied territory. The objectives of the study were achieved.
The use of the GROT type ground penetrating radars does not affect the environment and profitable, as it allows you avoiding excessive drilling.