Pathological change of stone is divided into external reason and internal reason.

Stone internal reason
Stone structure: nature stone exist micro crack and pore, with time going, stone will absorb the tiny dust and dirt from the air, through the stone pore, the dust and dirt will go into the stone internal place, greatly reduce the life of stone and its decoration performance. Stone pore is smaller, then stone absorption is stronger.

Stone contain complicated chemical component: some stone component are easy to react with outer circumstance. This cause stone erode and variation. Stone contain a certain quantity of iron usually, if contact with damp, it will occur rust. If the rust containing the more, then the chance to be rusty is more. Furthermore, the main component of most of marble are carbonate, calcium carbonate and Magnesium carbonate, and some little quantity of Alkaline oxide. calcium carbonate and Magnesium carbonate are comparatively more steady, in damp environment, is easy to have chemical reaction with Acidic oxide, like Carbon dioxide, Sulfur dioxide, Sulfur trioxide, nitrogen dioxide in the air. And it cause the change of the physical structure of marble. And it spoil the stone, make it become no luster, color fade, occur spot, and even cause the decrease of the hardness, surface Weathering and Flaking.  

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