Natural Rock-Egg: Red Tourmaline
Taken from CrystalDictionary.com:
“Rubellite” is a shocking pink or red tourmaline that behaves in a particular way in artifical light and daylight. This is to say, its color does not change depending on the light source, unlike many other gemstones. A true rubellite shines with equal intensity in daylight and artificial light. A red or pink tourmaline may be a rubellite, but not all red and pink tourmalines are, as most actually display a tinge of brown when exposed to artificial light. This stone is a rare example of inclusions being desired in a colored gemstone– only, however, if they are subtle and do not disturb the way light passes through the stone or make it appear milky or cloudy. Some noteworthy localities of rubellite include Brazil, Mozambique, Madagascar, Pakistan, Nigeria and the United States. They come almost exclusively from granite pegmatites. Rubellites are cut in various ways, depending on the intensity of the color of the particular specimen. They are probably among the most popular gemstones available on the market today. They tend to be found in vertically striated, prismatic crystals. Interestingly, heating or rubbing tourmaline can cause it to become electrically charged and form positive and negative ends. In the 1700s, dutch traders used it to pull ashes from their pipes. It exhibits a hardness of 7 to 7.5, a specific gravity of 2.9 to 3.3, a brittle tenacity, a vitreous luster, and can be transparent to opaque.