Image attribution: Free Use licence by user Sardaka on Wikimedia
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History
The former "Sun Newspaper Building" has facades on both Elizabeth Street and Phillip Street. It was built in the Gothic style but with Tuscan elements. It has a granite base with rendered walls above it. It is one three buildings in Sydney to feature this particular style, the others being the Grace Building on the corner of King and York Streets and.the State Theatre on Market Street.
The Granite used for the facade is from Uralla in the Northern Tablelands of New South Wales.
What is Granite? Granite is an igneous rock with grains large enough to be visible to the naked eye. It forms from the slow crystallization of magma below Earth's surface. Granite can be dark, red, pink, gray, or white in colour. It is a common rock used in building facades. You can read more about the formation and composition of granite at the Sydney Harbour Bridge Earthcache which features granite from Moruya on New South Wales south coast.
During the cooling process and whilst magma is still fluid, pieces of older rock may become included in the magma. If the rock was a foreign rock, it is called a xenolith. If it is genetically related to the magma, it is called an autolith, or an "enclosure". With either type, the magma cools around the rock and the xenolith or autolith becomes embedded within it.
At the listed co-ordinates, you will find a granite facade. If you look closely you will notice evidence of several other rocks in the granite that are embedded in the granite (that look like large spots or blotches) that have been exposed by the cutting and polishing process.
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Questions:
1. Observe closely one of the spots. Is it darker or lighter than the surrounding?
2. Observe the grains and texture of the spot selected. Are they similar to the surround rock, or are they or a markedly different material. How are they different?
3. Based on your observations, would you assess the spot as either a xenolith or an autolith.
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To log the earthcache, you may log a find as soon as you message the answers to me. If further information is required, I will message you back seeking clarification of your answers. Photos are not required for Earthcaches, but you are welcome to take a photo at the site. However, please do not include a photo of the spots.
Sources:
Heritage Listing entry by NSW Department of Environment