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Rocks have always been and continue to be used to construct buildings and infrastructure. They are generally used as dimension stone or crushed stone. Dimension stone Dimension stone is a natural stone or rock that has been selected and fabricated (trimmed, cut, drilled, ground, and so on) to specific size or shape. A variety of igneous, metamorphic, and sedimentary rocks are used as dimension stone. The favourites are granite, limestone, marble, travertine, quartz-based stone (sandstone, quartzite) and slate. In addition, rocks and stones that are not considered to be dimension stone are also available, such as tiles made of jade, agate, and jasper. A major plus of using dimension stones is “eco advantage”. Green building (environment-friendly construction) with natural materials has gained limelight these days. Dimension stone production is less energy intensive than that of concrete, aluminum and steel. It as an entirely natural product, and is recyclable and re-usable. 
Crushed stone Crushed stone or angular rock is a form of construction aggregate. Construction aggregates are coarse particulate material used in construction. They serve as reinforcements, and add to the strength of the basic materials. They are also used as foundation under roads and railroads. Crushed stone is the key component used in construction, agriculture, and other industries. It is usually produced by breaking a mined rock into the desired size using crushers. Thus, it is distinct from gravel, which is produced by natural processes of weathering and erosion. It substitutes the use of other aggregates like sand, gravel and slag (by-product of smelting ore to purify metals). Some rock structures have gained so much of fame that they have even become a “symbol” of the country they are built in. Can’t recall any names? Here’s one – Taj Mahal. Yes, Taj Mahal is built with rocks, specifically dimension stones – marble. Some Egyptian pyramids are also made of stones or rocks. Even the Great Wall of China is a series of stone and earthen fortifications. Apart from these monuments, rock gardens are also a world-favourite. A rock garden, also known as a rockery or an alpine garden, is a type of garden that features extensive use of stones, along with plants native to rocky or alpine environments. But, the Japanese rock garden is a special kind with hardly any plants. And in India, the Rock Garden in Chandigarh is a sculpture garden. Spread over an area of forty acres, it is completely built of industrial and home waste and thrown-away items! AS TREASURE Rocks are treasure troves. Literally. Some are valued for their beauty or aesthetic sense. These are called gemstones. Gems (also called precious or semi-precious stones) are pieces of attractive mineral, which are used to make jewellery and other adornments after cutting and polishing. However, certain rocks, such as lapis-lazuli are not minerals, but are often considered as gemstones. Rarity is another characteristic that lends value to a gemstone. ROCKING ENVIRONMENT So, aren’t rocks simply incredible? But do you know that even the slightest change in the environment can spell doom for them? Remember the rock cycle? Yes, the changing of one rock type into the other. This is a natural process that depends mainly on the forces of wind and water. They help to erode and weather rocks. Weathering is the process of chemical or physical breakdown of rock minerals. Erosion, on the other hand, is the carrying away (displacement) of rocks by forces like wind and water. But, the two processes may be concurrent. Erosion is greater in areas with highly weathered rock. The rate of erosion is affected by various factors. One of them is human activity. Poor land use practices like deforestation, overgrazing, and unmanaged construction activity destroy the ground cover from vegetation. This exposes the rocks to the forces of erosion. Further, changes in the climate, such as the average temperature, and the amount and intensity of rain, worsen the situation.
The removal of large amounts of rocks from a particular region, and its deposition elsewhere, can alter the load on the lower crust and mantle. This can cause tectonic uplift in the eroded region. In other words, the land would rise to compensate the loss of weight of rocks. As for weathering, one of the major factors that accelerate its pace is acid rain – any form of precipitation that is unusually acidic. The acid deposition may be wet (rain, snow, sleet, fog or dew) and dry (acidifying particles and gases) acidic components. Apart from adversely affecting our health, forests, freshwaters and soils, killing insect and aquatic life forms, acid rains damage structures, especially those made of rocks. And mountainous regions are the most-affected, simply because they get more rainfall. This poisonous precipitation is mainly caused by human emissions of primary air pollutants, mianly sulphur and nitrogen compounds. These react in the atmosphere to produce acids like sulphuric and nitric acid. The main sources of these pollutants are industrial power-generating plants and vehicles. So you see, rocks shape our lives and we shape theirs. Most often, through activities that affect rocks adversely. It may be pollution, climate change or deforestation, all erode and weather away these treasure troves. |
The beauty of rocks is also revealed through art. 
