Adopt-a-Mineral Project:
Silver and Rutile
Greg Gantz

www.emporia.edu/earthsci/amber/
go336/gantz/

Impact Created Minerals:
Fulgurites and Shock Quartz
Greg Gantz

www.emporia.edu/earthsci/amber/
go336/gantz/fulgurites.htm

This webpage is to provide a brief description of two minerals investigated in my mineralogy class, www.emporia.edu/earthsci/amber/go336/ at Emporia State University. An introduction will be followed by specific information on silver and rutile.

Minerals have become part of the scientific vernacular in the past several centuries. This is in large part thanks to the efforts of three scientists in the late 1700s and early 1800s. Georg Bauer, Nicolas Steno, Rene Haüy developed the basic concepts of what a mineral is and their definitions have stuck (Wenk 4). A mineral by definition is a homogenous, naturally occurring, inorganic solid; each mineral has its own definite unique chemical composition, and a characteristic crystalline structure (Chesterman 4-5). Silver is one of over 4,000 minerals that have been discovered to date.

Silver

Silver is what is known as a native element. That is because it is a mineral and an element on the periodic table. While silver and other elements are bonded together to create minerals, silver appears most commonly in its elemental state or Ag (Chesterman 347).

The image left is native or elemental silver. The image is borrowed from Amethyst Galleries Native Silver webpage, http://www.galleries.com/minerals/elements/silver/silver.htm.

Silver has a hardness of 2.5-3 on the Mohs' Hardness scale. It is metallic, with a grayish shiny streak. Silver’s specific gravity is very high at around 10.1 to 11.1. Silver is a member of the Isometric crystal class, with the most common form being octahedrons (Chesterman 347). Silver appears widely throughout the world. It most commonly appears in volcanic rocks. It can appear in either small amounts or in large sheets. Silver ore is mined and used for photographic and jewelry purposes, primarily (Chesterman 347).

Rutile

Rutile’s chemical composition is TiO2. Its crystal form is prismatic with well defined faces (Wenk 420). The name rutile is derived from the Latin rutilus, which means red. That is a good clue as to the most common color for rutile in nature. Of course, that color is red (Webmineral.com). This physical characteristic can be deceiving though as not all rutile specimens are red in color. Rutile can also be found in brown to black colors, and adamantine to sub metallic luster varieties. Color is also not a clear indication of the streak because the streak of rutile is white, which may seem counterintuitive (Chesterman 400).

Image to the right is of yellow acicular rutile crystals on hematite, taken from http://www.webmineral.com/data/Rutile.shtml

Rutile is part of a much larger sub group of minerals known as the oxides. Oxides are minerals that have a metal bonded with and oxide atom. In the case of rutile the metal is titanium (Chesterman 400). Oxides are a common chemical group of minerals, because they appear to form at all levels of the earth.

Sources

  1. Chesterman, C.W. 1978. The National Audobon Society Field Guide to the North American Rocks and Minerals. Alfred A. Knopf: NY.
  2. Webmineral.com (n.d.) Rutile Mineral Data. Retrieved August 29, 2007, from www.webmineral.com/data/Rutile.shtml
  3. Wenk, Hans-Rudolf, and Andrei Bulakh. 2004. Minerals: Their Constitution and Origin. Cambridge University Press: Cambridge, U.K.


Return to GO336 Student Webpages, www.emporia.edu/earthsci/amber/go336/webpages.htm. Webpage created October 2007; last update November 27, 2007.