Andalusite is a highly prized collector’s gemstone. It exhibits an optical property known as pleochroism. As the stone is turned or rotated, it exhibits different colors, or blends of colors depending on the angle of viewing. This property is so strong that the color contrast is incredibly striking: earthy, olive greens to rich, reddish browns. Cut [..]

<chemical> A silicate of aluminium, occurring usually in thick rhombic prisms, nearly square, of a grayish or pale reddish tint. It was first discovered in Andalusia, Spain. (01 Mar 1998)