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.
Once the building is about 180 feet tall (some 15 stories), the crane is fastened to the building with steel collars, and new segments are inserted into the craneâs backbone. To add segments to itself, the crane has a special climbing sectionâa big metal sheath that scales the outside of the crane tower.he crane stands inside the center of the building, in a kind of makeshift courtyard, where it constructs the skyscraper around itself about a hundred feet at a time. A hydraulic cylinder at the craneâs base elevates it through the hollow middle of the building to a higher floor.