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…showed last 75 words of 327 total…is 77 and its atomic weight is 192.22. It melts at 2410 C and boils at 4130 C. It has a density of 22.65 grams per cubic centimeter at 20 C. Metallic Iridium has a face-centered cubic crystalline structure. Iridium belongs to the group of metals called transition metals. Its name is derived from the Greek goddess Iris, goddess of the rainbow, because the salts of the metal are brilliantly colored. Smithson Tennant, a British chemist, discovered Iridium in 1804. ------------------------------------------------------------------------ **Bibliography**