Watch the world's greatest cities rise and fall over the past 4,000 years. 1  These are the 25 most high-tech cities in the world. 2  Scientists have cracked Rome's secret to waterproof concrete. 3  These mega-projects will transform the world's greatest cities by 2030. 4  The inequality we're not talking about: house prices.
When it comes to makeup, color is the name of the game. Minerals provide the color to eyes, cheeks, lips, and nails. Iron oxide, one of the most important color minerals, was used by Cleopatra in the form of red ochre as rouge. Today, iron oxides give red, orange, yellow, brown, and black tones to makeup. Chrome oxides are used for greens; manganese violet for purple; ground lapis lazuli may be added to makeup for blue.
A variety of imperial topaz, this purple crystal is a rather rare color of the topaz mineral. Varying from light violet to deep purple, the violet crystal gets its color from the inclusion of chromium into the otherwise colorless mineral. Topaz in general is the gemstone of the zodiac sign Sagittarius. gemstone found in all the colors of the rainbow, tourmaline also occurs as purple stones. These purple crystals come from the species of tourmaline called elbaite, including the highly valuable Paraiba tourmaline.