Most earthcaches are either based on Granite, Limestone or Marble.
Granite
Granite is a kind of igneous rock, found on Earth but nowhere else in the Solar System. It is formed from hot, molten magma. Its colour ranges from pink to grey, according to the proportions of its minerals.
The magma is forced between other layers of rock by the pressure under the Earth's surface. The magma cools and turns slowly into solid stone. Granite has many different types of minerals in it. These include quartz, feldspar, hornblende, and sometimes mica. As the magma cools, these minerals form crystals. The crystals can be seen easily if the granite is cut and polished.
Granite is a common stone on Earth, and makes up a big part of the crust (the Earth's outer layer). It is usually found in the continental plates of the Earth's crust. Although it forms under the surface of the Earth, there are many places where it has been forced upwards by tectonic movement. When plates in the Earth's crust move together, they get bent and pushed upwards. When this happens, granite mountains can be formed.
Limestone
Limestone is a sedimentary rock, which means it was formed from small particles of rock or stone that have been compacted by pressure. Sedimentary rock is important because it often contains fossils and gives clues about what type of rock was on the Earth long ago. Just like a tree's rings tell a lot about its environment, layers found in sedimentary rock can tell about important changes in the environment.
Limestone is formed in two ways. It can be formed with the help of living organisms and by evaporation.
Ocean-dwelling organisms such as oysters, clams, mussels and coral use calcium carbonate (CaCO3) found in seawater to create their shells and bones. As these organisms die, their shells and bones are broken down by waves and settle on the ocean floor where they are compacted over millions of years, creating limestone from the sediments and the pressure of the ocean water.
The second way limestone is formed is when water containing particles of calcium carbonate evaporate, leaving behind the sediment deposit. The water pressure compacts the sediment, creating limestone.
Because limestone is often formed from shells and bones, it is a light colour like white, tan, or grey. The colour of the limestone depends on the other sediments in the mixture besides the mineral calcite, which is white; impurities such as sand, clay, and organic material are also present in limestone and affect the colour.
There are a few ways to recognise limestone. First of all, it is a soft stone and when it is scratched with a sharp object, it becomes a white powder. When limestone comes in contact with an acid like vinegar or hydrochloric acid (HCl), the stone will actually bubble and deteriorate and then neutralise the acid.
Marble
Have you ever noticed beautiful, white, stone statues or sculptures at museums or fancy buildings? You may have also noticed this stunning stone at homes on floors, stairways, counters, or on a gorgeous fireplace. This elegant stone or rock is called marble.
Marble is a type of natural stone found on Earth and is usually white, although different colours and patterns may be found in it.
The different colour lines on it can look like they were painted on the marble. But actually, these designs are already IN the marble when it is found and mined!
Marble is a metamorphic rock, which means it has gone through a metamorphosis, or a change. This change happens when heat and pressure that naturally happens inside or on Earth's surface changes a rock over thousands of years.
Marble starts out as limestone rock, which is made of hardened fossils, and then heat and pressure changes it into marble. In nature, marble can develop to be very large rocks, up to hundreds of feet in size!
Marble is made of tiny minerals called calcite or dolomite. Sometimes, small amounts of other minerals like quartz and mica are found in marble, which gives it various natural colours, patterns, or designs.
Even though marble is usually white, it can also come in a variety of colours and designs including black, yellowish-brown, blue-grey, green, pink, and red.
At GZ you will find a sculpture, please email your answers to the following questions.
Q1: Using the information in the description, What 2 types of rocks were used to make this sculpture? How do you come up with this answer?
Q2: How many different colours do you see throughout the sculpture?
Q3: Did the artist sign the sculpture? If so where did they sign it?
Any "Found it" logs for which answers have not been received will see that log discreetly deleted.