Welcome to the Black Sands of Mackay Earthcache
GZ has moved up the beach a bit, this is a natural phenomenon (longshore drift). The black sand is still visible and you wont have a problem locating it.
Sand
The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in is silica (silicon dioxide, or SiO2), usually in the form of quartz. The second most common type of sand is calcium carbonate, for example, aragonite, which has mostly been created, over the past half billion years, by various forms of life, like coral and shellfish.
Black Sand Beaches are made up of " heavy minerals", which come from volcanic rocks.
When lava contacts water, it cools rapidly and shatters into sand and fragmented debris of various size. Much of the debris is small enough to be considered sand.
That's why black sand beaches are found in volcanic locations such as Hawaii , New Zealand, Santorini and the Canary Islands.
Even our beaches contain black sand from Australia's volcanic past but you often don’t notice it because , being heavier , the black sand minerals have winnowed their way down through the lighter coloured quartz sand, forming layers well below the surface.
Volcanic minerals and lava fragments commonly have magnetite in them. Magnetite is a naturally occuring type of iron oxide that is magnetic.
Organic particles such as coal dust are also black.
Lets perform a few simple experiments to determine the source of the "black" in the sand , to do so you will need . A Magnet, white or light coloured paper and a writing implement of your choice
To log this cache you must supply the following answers to us, the "Message this owner" link at the top of the page is preferred. Then log your find as usual. If we have any issues about your supplied information, we shall contact you back. In the meantime, I hope you enjoy your visit to “The Black Sands of Mackay" just as much as we did back in August 2020.
1. Observe the sand at this location and provide a brief description .
2. How deep is the layer of black sand at this location ?
3. Rub the sand onto the paper lightly with your finger, an organic material like coal would mark the paper. Is the black sand here an organic material such as coal ?
4. Place a small quantity of sand ( teaspoon ) onto a sheet of white or light coloured paper, pass a magnet through the sand . What do you observe? What mineral do you think makes up the black sand?
5. A photo at GZ to prove you were here, maybe you could write your name in the sand.
Remember that sand is a non-renewable resource,leave your sample behind.
FTF joint honours go to OzGeoker and Geogirl4740.