Chemical composition -- Titanium oxide.
Color -- Brownish-red to black.
Optics -- R.I. 2.62-2.90. Metallic to adamantine luster.
Durability -- Hardness 6-6.5.
Crystal structure -- Tetragonal.
Specific Gravity -- 4.2.
Sources -- Brazil, George, Arkansas, North Carolina, other locations. Usually found as needle-like crystal inclusions in quartz (rutilated quartz) or agate (sagenite) and in many other materials.