Antimony is what you would call a semi-metal or metalloid. In other words, it resembles a metal in appearance and in many of its physical properties. However, it does not react as other metals do. Other metalloids include arsenic, silicon, germanium, boron, tellurium, and polonium. Generally, elements to the right of these on the periodic table are considered nonmetals and elements to the left are considered metals. In terms of its metallic properties, antimony is a poor conductor of both heat and electricity. For example it has about 5 percent of the thermal conductivity of copper and less than 4 percent the electro-conductivity. Also, unlike other metals, it is fragile and quite brittle. Finally, to further mark the difference between metals and metaloids, the mechanical strength of antimony decreases with increases in purity.