Taxonomy term


Mineral Resource of the Month: Mica

The mica mineral group includes 34 phyllosilicate minerals, all with a layered, platy texture. The mineral has been known for millennia: Mica was first mined in India about 4,000 years ago, where it was used primarily in medicines. The Mayans used it for decorative effect in stucco to make their temples sparkle in the sun. Today it is used in everything from electrical products to makeup.

22 Nov 2014

Mineral Resource of the Month: Vermiculite

Vermiculite comprises a group of hydrated, laminar magnesium-aluminum-iron silicate minerals resembling mica. They are secondary minerals, typically altered biotite, iron-rich phlogopite or other micas or clay-like minerals that are themselves sometimes alteration products of amphibole, chlorite, olivine and pyroxene. Vermiculite deposits are associated with volcanic ultramafic rocks rich in magnesium silicate minerals, and flakes of the mineral range in color from black to shades of brown and yellow. The crystal structure of vermiculite contains water molecules, a property that is critical to its processing for common uses.

16 Sep 2014

Mineral Resource of the Month: Selenium

Selenium, a relatively rare element with diverse uses, is widely distributed within Earth’s crust, but it does not occur in concentrations high enough to justify mining solely for its recovery. Selenium is recovered as a byproduct of nonferrous metal ore processing, principally from the anode slimes associated with electrolytic refining of copper. Slimes from primary copper refining can contain as much as 10 percent selenium, but are generally much lower.

12 May 2014

Mineral Resource of the Month: Wollastonite

Wollastonite, a calcium metasilicate, has an ideal composition of 48.3 percent calcium oxide and 51.7 percent silicon dioxide, but it can also contain minor amounts of aluminum, iron, magnesium, manganese, potassium, sodium or strontium substituting for calcium. Wollastonite occurs as prismatic crystals that break into tabular-to-acicular fragments. It is usually white but also may be gray, cream, brown, pale green, or red depending on its impurities and grain size.

14 Apr 2014

Mineral Resource of the Month: Talc

When people think of talc, they often think of talcum and baby powder. However, these uses of talc are minor compared to its use in industrial manufacturing. The leading use of talc in the United States is in the production of ceramics, where it is a source of magnesium oxide, serves as a flux to reduce firing temperatures, and improves thermal shock characteristics of the final product. Worldwide, the major use of talc is as a paper constituent, where it fills the interstices between cellulose paper fibers, reduces paper transparency, improves ink receptivity, and absorbs undesirable tree sap residues that can generate blemishes in the paper.

03 Mar 2014

Mineral Resource of the Month: Iron and Steel

Iron is one of the most abundant elements on Earth, but it does not occur in nature in a useful metallic form. Although ancient people may have recovered some iron from meteorites, it wasn’t until smelting was invented that iron metal could be derived from iron oxides. After the beginning of the Iron Age in about 1200 B.C., knowledge of iron- and steelmaking spread from the ancient Middle East through Greece to the Roman Empire, then to Europe and, in the early 17th century, to North America. The first successful furnace in North America began operating in 1646 in what is now Saugus, Mass. Introduction of the Bessemer converter in the mid-19th century made the modern steel age possible.

03 Feb 2014

Down to Earth With: Sally Jewell

Most people who find their way into public office start locally, perhaps by running for a seat on the school board or city council. Sally Jewell’s first foray into public service came at the behest of President Obama, who last year nominated her as the 51st Secretary of the Department of the Interior (DOI) — the first Secretary in more than a decade with a background in geoscience.

28 Jan 2014

When water, gravity and geology collide: Firsthand observations of the impacts of the 2013 Colorado floods

Around almost every bend in the road on our tour of the Colorado Front Range and points downstream in the weeks after the September floods, the physical devastation confronted us like a punch in the gut. Even though we had all seen graphic images on the news, observing the destruction firsthand, especially from a geologic perspective, was truly stunning and humbling.

21 Jan 2014

Mineral Resource of the Month: Phosphate Rock

As a mineral resource, “phosphate rock” is defined as unprocessed ore and processed concentrates that contain some form of apatite, a group of calcium phosphate minerals that is the primary source for phosphorus in phosphate fertilizers, which are vital to agriculture.

02 Dec 2013

Mineral Resource of the Month: Thallium

Thallium, a grayish-white metal similar to tin in appearance, was discovered spectroscopically in 1861. Like lead, it is heavy yet soft, and can be cut easily with a knife. When exposed to air, thallium’s luster quickly tarnishes to a blue-gray color owing to the formation of a film of thallium oxide. Its concentration in Earth’s crust is estimated at 0.7 parts per million; mostly it is found in association with potassium minerals in clays, soils and granites, but in general it is not commercially recoverable from those sources. Manganese nodules, found on the ocean floor, also contain thallium.

04 Nov 2013