At GZ you will find a marble sculpture which is a tribute to and a commemoration of Steve Irwin, local wildlife warrior and renowned conservationist the world over. The artwork was sculptured by Silvio Apponyi and depicts Steve with his son Robert and daughter Bindi.It is carved out of Queensland marble and was unveiled to the public on 4 December 2007.
What is Marble?
Marble is a metamorphic rock that may be foliated or non-foliated, composed of recrystallized carbonate minerals, most commonly calcite or dolomite.
Geology of Marble
Most marble forms at convergent plate boundaries where large areas of Earth's crust are exposed to regional metamorphism. Some marble also forms by contact metamorphism when a hot magma body heats adjacent limestone or dolostone.
Before metamorphism, the calcite in the limestone is often in the form of lithified fossil material and biological debris. During metamorphism, this calcite recrystallizes and the texture of the rock changes. In the early stages of the limestone-to-marble transformation the calcite crystals in the rock are very small. In a freshly-broken hand specimen they might only be recognized as a sugary sparkle of light reflecting from their tiny cleavage faces when the rock is played in the light.
As metamorphism progresses the crystals grow larger and become easily recognizable as interlocking crystals of calcite. Recrystallization obscures the original fossils and sedimentary structures of the limestone. It also occurs without forming foliation which normally is found in rocks that are altered by the directed pressure of a convergent plate boundary.
Recrystallization is what marks the separation between limestone and marble. Marble that has been exposed to low levels of metamorphism will have very small calcite crystals. The crystals become larger as the level of metamorphism progresses. Clay minerals within the marble will alter to micas and more complex silicate structures as the level of metamorphism increases.
Physical Properties and Uses of Marble
Marble occurs in large deposits that can be hundreds of feet thick and geographically extensive. This allows it to be economically mined on a large scale with some mines and quarries producing millions of tons per year.
Most marble is made into either crushed stone or dimension stone. Crushed stone is used as an aggregate in highways, railroad beds, building foundations and other types of construction. Dimension stone is produced by sawing marble into pieces of specific dimensions. These are used in monuments, buildings, sculptures, paving and other projects.
Colour: Marble is usually a light-coloured rock. When it is formed from a limestone with very few impurities it will be white in colour. Marble that contains impurities such as clay minerals, iron oxides or bituminous material can be bluish, grey, pink, yellow or black in colour.
Marble of extremely high purity with a bright white colour is very useful. It is often mined, crushed to a powder and then processed to remove as many impurities as possible. The resulting product is called "whiting". This powder is used as a colouring agent and filler in paint, whitewash, putty, plastic, grout, cosmetics, paper and other manufactured products.
Acid Reaction: Being composed of calcium carbonate, marble will react in contact with many acids, neutralizing the acid. It is one of the most effective acid neutralization materials. Marble is often crushed and used for acid neutralization in streams, lakes and soils.
It is used for acid neutralization in the chemical industry. A pharmaceutical product known as "Tums" is a small calcium carbonate pill, sometimes made from powdered marble, that is used by people who suffer from acid reflux or acid indigestion. Powdered marble is used as an inert filler in other pills.
Hardness: Being composed of calcite, marble has a hardness of three on the Mohs hardness scale. As a result, marble is easy to carve and that makes it useful for producing sculptures and ornamental objects. The translucence of marble makes it especially attractive for many types of sculptures.
Ability to Accept a Polish: After being sanded with progressively finer abrasives, marble can be polished to a high lustre. This allows attractive pieces of marble to be cut, polished and used as floor tiles, architectural panels, facing stone, window sills, stair treads, columns and many other pieces of decorative stone.
To Log this earthcache you have study the sculpture and answer the questions listed below. PLEASE EMAIL THE ANSWERS TO ME BUT DO NOT POST ANY ANSWERS WITH YOUR LOG.
Q1. Why do you think this material was used for the sculpture?
Q2. Are there any areas that are rougher in texture than others? Why and how do you think this was done?
Q3. Q3. What do the children have in their pockets? Describe what you find and the describe the texture.
MANDATORY TASK – A photo of you or a body part or your GPS at the statue. Post this picture with your online log.
You do not need to wait for a confirmation email to log your find. I read all emails to verify the correct information has been obtained and I will contact you if there are any problems with your answers. Failure to provide an email with answers to the questions and mandatory photo may result in your log being deleted.