Langkawi has a long history in its creation. Therefore different typs of rocks on its surface exist: 4 different typs of sedimentary rock and one granite formation.
Langkawi belonged at first to Gondwana. Later it drifted south and submerge under sea level. At the end of the end of Permian all different types of sedimentary rock had formed. Then some tectonic events took place and lifted Langkawi above sea level. This ended with the emplacement of granite beneath the Langkawi crust at the end of the Triassic. Now the middle of Langkawi Island consists mostly of Gunung Raya granite (named after the highest mountain on Langkawi).
Granites form by the solidification of molten magma within the earth crust, usually at a depth of more than 2 km below the surface. In this process different minerals solidify according to their melting temperatures creating crystal grains in the granite. This gives most granites, more precisely porphritic granites, their grainy structure.
Langkawi granite is predominantly made of porphyritic granite containing minerals such as mainly tourmaline and ilmenite, less zircon and garnet which are all dark to black in color. These minerals are washed out with the rain and run down by the spring water from the mountains. During the wet season it is blacker as the mineral deposits persistently wash up on the shore and cause the color of sand to turn black.
But this phenomena seems to be an exception in Langkawi. It has been observed by the scientists that these minerals rarely cause sand to turn black elsewhere in the world. Granitic beaches are generally characterised by the presence of boulders, which display naturally sculptured forms. They also tend to have a higher proportion of coarse grains giving the sand a gritty feel.
For a log you have to send me the answers to the following questions:
1. What happens if you dig a bit in the black sand? Is the sand black or changes it color?
2. Guess, why.
A picture of you near the location will be nice, but it is only optional. You don´t have to wait for an answer to log.
A log without sending the answers will be deleted. An online log with the answers in it will be deleted too without notice!
Have fun!
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