Stone


 * What are stones?**

Stones are a type of organic material found all over the earth. It could be really strong, so mankind have used it for contruction.


 * How many kinds of stone do you know?**

Marble, granite, sandstone and limestone.


 * What characteristics do stones have?**

They could be really strong and could be shaped.


 * Why are stones used in construction?**

They are easily found in some places and are decorative and structural at the same time.

Stone is a material often used in construction because it is durable, adaptable to sculptural treatment and used naturally. But, on the other hand it is difficult to quarry, transport and cut. It is considered to be weak in tension, **so its use for beams and other support structures is limited. **In addition it is unstable with loads pushing at angles. Notwithstanding it could be expensive. The stonework could be made through rubble, **which is the cheapest and simplest **, or ashlar masonry, **which is the strongest and most suitable for monumental construction **. Rubble provides mortar-bounded broken stones, while ashlar masonry provides regularly cut blocks **(usually rectangular) that in contrast with bricks do not depend on strong bonding for stability. ** Stones have been used for construction since the stone age, clearly seen in stonehenge. **Even though nowadays it has been partly replaced for new materials, it is still used for being practical and expressive. **

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