NOTE: Maps and tourist information for this area is readily available from Cloncurry and Mount Isa information centres. The roads here are not maintained. It may be best to park the caravan/trailer at the old townsite before proceeding to the mines.
Uranium is the heaviest naturally occurring element and is plentiful in the Earth's crust, showing up in anything from granite rocks to seawater. It has been estimated that the oceans of the world contain 4,000 million tonnes of uranium.
Even so, it is a moderately rare element. Its abundance is estimated to be about 2 to 4 parts per million, making it more abundant than silver or mercury, about the same as tin and slightly less that cobalt or lead.
Uranium is a silvery, shiny metal that is both ductile and malleable. At one time, uranium was considered to be a relatively unimportant element. It had a few applications in the making of stains and dyes, in producing specialized steels, making coloured glass and in lamps.
Then, a dramatic revolution occurred. Scientists discovered that one form of uranium will undergo nuclear fission. Nuclear fission is the process in which the nuclei of large atoms break apart. Large amounts of energy and smaller atoms are produced during fission.
The first application of this discovery was in the making of nuclear weapons such as the atomic bomb. After the war, nuclear power plants were built to make productive use of nuclear fission. Nuclear power plants convert the energy released by fission to electricity. A 30 gram pellet of uranium dioxide is equivalent in energy to between 2 and 3 tonnes of coal or 10 barrels of oil.
Today, uranium is regarded as one of the most important elements for the future of the human race. Some of its many uses include medicine, preservation of food, detection of pollutants in the environment and in industry. Its radioactive decay provides the main source of heat inside the Earth, causing convection and continental drift.
The Mary Kathleen orebody was discovered on July 4th, 1954. It is located in the Cloncurry Mineral Field about 55km due east of Mount Isa and 800km due west from Townsville, the sea port. There are the obligatory warning signs but the area is safe to visit.
The mined ore occurred in amphibolite metamorphic rocks which belong to the Corella Formation of Carpentarian Age (Middle Proterozoic). The original sediments were deposited in the Eastern Trough of the Mount Isa geosyncline. The rocks have been intruded by granites and suites of acid and basic dykes.
The basement of the mine was deposited about 1780 million years ago. The original sediments were most probably shallow water marls and shales with occasional sandy intercalations.
During metamorphism, the rocks were tightly folded into the Mary Kathleen syncline. Current thinking is that the mineralisation was concentrated earlier in the geological history of the syncline and may be related to centres of basic volcanism.
The host to the orebody is a massive zone of garnet known locally as garnetite. Other rock forming minerals found in Mary Kathleen included hornblende, uraninite, prehinite, chalcopyrite, quartz and calcite. There are several other abandoned mines in the vicinity of Mary Kathleen indicating the geological variances in the area. One of them is the nearby Sunset Mine.
You may log this Earthcache straight away but then please email your answers to the questions to the CO. We will contact you ONLY if your answers need extra work. Logs with no answers sent will be deleted. The answers can be found by observing the landscape and a bit of research.
Q1. What is the chemical symbol for uranium?
Q2. A major ore of uranium is pitchblende. True or false?
Q3. What sort of mine is Mary Kathleen? shaft, open cut, shallow pit
Q4. Walk on the tier level to the further side of the mine lake to S20 44.805 E140 00.810. Look closely at the rock wall. What are the predominant colours and texture?