A polished slab of a stone that geologists are still arguing about.
The textbook explanation, written in 1873, is that quartz slowly replaced asbestos fibres and inherited their shape. In 2003 that was challenged. Quartz crystals inside tiger's eye run up to 10 millimetres long, and fractures cut through quartz and fibre alike, which suggests the two grew together rather than one replacing the other. South African geologists working these deposits replied the following year. Tiger's eye turns up only where an ancient erosion surface cuts the veins, and none is found at depth, which points to weathering instead.
Neither side has given ground. It is an unusually plain-looking stone to have an open question attached to it.
Mineral: Tiger's eye (a variety name, not an IMA species), quartz (SiO₂) with fibrous riebeckite (crocidolite)
Crystal system: Trigonal
Origin: Northern Cape, South Africa
Hardness: 6.5 to 7 on the Mohs scale; durable, though the polished face dulls if knocked about
Treatment: None to the stone. Resin stabiliser applied around the edges
Dimensions: 8.57 x 1 x 28 cm
Weight: 595 g Note: Do not cut, grind or sand it. The fibres running through tiger's eye are crocidolite, locked into the quartz and inert in a finished slab, but power tools release them as dust.
You will receive the exact piece photographed.