One of the most famous and most photographed geologic sites in the world is the banded ironstone formation.
Hematite is commonly seen as a gray mineral, however it can also form as a brown, brownish red, bright red, or shiny black color. It can form as tabular or rhombohedral crystals, sometimes forming a rose shaped mass called an iron rose, which is highly collectible. Other habits include massive, crusty, granular, radiating fibrous, and reniform or botryoidal. Specular hematite or Specularite has aggregates of silvery, metallic, flakes or tabular, anhedral crystals.
Specular hematite or specularite as photographed from two different angles.
Hematite has several uses, one of the most common being as an ore of iron. It has also been used in polishing powders, and included in red paint since ancient times. The Aztecs used the specular hematite as mirrors by grinding it up and creating polished flat pieces. Hematite is also found in jewelry, though most of the beads available are manmade/synthetic hematite.
Most hematite used in jewelry is actually synthetic, often called Hemalyke.
If you have a stone you would like to know about, please feel free to leave a request in the comments section. Have a mystery stone? Leave a link in the comments to a picture of it, and it may be featured as a part of this series!
Chemical composition: Fe2O3
Color: Brown, Brownish Red, Red, Gray, Black
Habit: Crystals, massive, granular, earthy, fibrous, reniform or botryoidal
Luster: Dull, Metallic
Hardness: 6.5 (crystalline)
Specific Gravity: 5.3
Streak: Red, Brownish Red
Occurrence: Worldwide, abundant in the Lake Superior region
A Guide to Rocks and Fossils by B. Busbey III, R. R. Coenraads, P. Willis, and D. Roots. Published 2002 by Fog City Press. ISBN: 1877019518
Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966
Mindat – Specularite. http://www.mindat.org/min-5574.html
Wikipedia – Hematite. http://en.wikipedia.org/wiki/Hematite