Emeralds are gem-quality specimens of the beryl mineral family with a rich, distinctly green color. They are found in igneous, metamorphic, and sedimentary rocks in a small number of locations worldwide. For over 5000 years, emeralds have been one of the most desirable and valuable colored gemstones.
For example, the Agway Elevator was built on a concrete mat 3 feet thick which in turn rests on a natural foundation of stiff clay. But whatever the foundation for the elevator was, be it wood pilings or concrete slabs, construction of the elevator itself could begin once the base was completed.
CONCRETE FRAME STRUCTURES. Concrete frame structures are a very common-or perhaps the most common-type of modern building. As the name suggests, this type of building consists of a frame or skeleton of concrete. Horizontal members of this frame are called beams, and vertical members are called columns. Humans walk on flat planes of concrete called slabs. Of these, the column is the most important, as it is the primary load-carrying element of the building (See figure 2 at the bottom of the page for an illustration of each of the major parts of a frame structure).