Jasper is an opaque and finely crystalline variety of quartz. The chemical compositions are identical to those of agate, flint, and chert. The colours are variable, from yellow through red and red-brown to green. Jasper stones are cut and polished to be set in jewellery. The name jasper is derived from Latin and Greek (íaspis) from a Semitic language and means "spotted or speckled stone". The most important sources of jasper are India (Dekkan Plateau) and Mexico (yellow); Germany (red); and Africa, Australia, Brazil, Egypt, France and the US (other colours). Jasper has been used as a gemstone since ancient times. For example, seal stones, small cut stones and trinkets were made from it. Jasper was attributed with magical powers. In ancient times it was called the mother of all stones. Today it is used in cabochons, tableware and crafts. Imitations are made from glass. The Egyptians and Greeks already used jasper to enhance sexuality and to achieve a quick pregnancy. Among the Indians, yellow jasper worked as a rain stone. Jasper is attributed with a number of medicinal properties, such as stress reduction, weight loss, stomach complaints and liver problems. According to various literary sources, jasper belongs to the zodiac signs Aries, Virgo, Cancer and Scorpio. In the Christian scripture Revelation 4:2-3 it is written: (2) At that moment I was in the spirit. And there was a throne set in heaven, and one sat on it. The appearance of the one sitting was like that of jasper and jade, and around the throne was a rainbow in appearance like an emerald.