Quantcast
Gemstones 250x250

The Mineral anglesite

Lustrous Yellow Anglesite Crystal

Anglesite is a secondary lead mineral that always forms through the alteration of lead sulfides, primarily Galena. Anglesite crystals may contain impurities of Galena, giving a specimen a gray to black color. In some localities, Anglesite forms as a pseudomorph after Galena, giving the crystals a false isometric form.

Gray and black banding is present in some massive Anglesite specimens, which can be seen when a specimen is polished or sliced. Such specimens may even contain unaltered Galena in the center, which did not change over to Anglesite when the outer layers altered. An amber-red Anglesite from Touissit, Morocco, has been synthetically colored by immersing light yellow crystals in bleach.


Anglesite is named for its type locality at the Parys Mine, on the Island of Anglesey, Wales, in the United Kingdom.

Chemical Formula

PbSO4

Color

Colorless, white, yellow, brown, green, orange, red, gray. May also be black from Galena impurities, which can also cause it to be banded gray and black. Sometimes multicolored with yellow and white or colorless zoning.

Crystal System

Orthorhombic

Properties

Streak
White, but light gray if it has Galena impurities.
Hardness
2.5 - 3
Transparency
Transparent to translucent in thin splinters
Specific Gravity
6.4
Luster
Adamantine, resinous
Cleavage
2,1 - basal ; 3,1 - prismatic
Fracture
Conchoidal
Tenacity
Brittle
Other ID Marks
Commonly fluorescent light yellow in shortwave ultraviolet light.

Crystal Habits

Most often in tabular or prismatic crystals, sometimes elongated. Anglesite crystals often have very distinct pointed terminations. Crystals may also be bipyramidal, and are frequently striated, with a tendency for one crystal side to have more striations than the other. Also grainy, crusty, massive, reniform, and stalactitic. Anglesite is unique in that it never forms pseudohexagonal trillings as other members of its group do. Anglesite may form pseudomorph after other minerals, especially Galena and Cerussite, which may give it the additional shapes and forms of the host mineral.

3D Crystal Atlas

Additional Information

Composition
Lead sulfate
In Group
Sulfates; Anhydrous Sulfates
Striking Features
Unusual heaviness, adamantine luster, mineral associations, and untwinned crystals.
Environment
Anglesite is a secondary mineral forming in weathered lead deposits.
Rock Type
Metamorphic

Uses

Anglesite is an ore of lead, although good crystals are preserved when possible, due to the high demand and cost of good specimens.

Noteworthy Localities

Very large Anglesite crystals were found in Tsumeb, Namibia; and some of the finest gemmy crystals came from both Mibladen and Touissit, Morocco, including the bright golden-yellow type. Other well-known localities are the Monteponi and Montevecchio Mines, Sardinia, Italy; and Broken Hill, New South Wales, Australia. The original locality of Anglesite, after which this mineral is named for, is Parys Mountain, Amlwch, on the Isle of Anglesey in Wales, United Kingdom. Specimens from this mine are very old and are considered exceptional classics.

Three Mexican Anglesite occurrences of note are the Ahumada Mine, Sierra de Los Lamentos, Chihuahua; the Santa Eulalia District, Chihuahua; and San Felipe, Aconchi, Sonora.

In the U.S., white crystals associated with Pyromorphite have come from the Wheatley Mines in Phoenixville, Chester Co., Pennsylvania. The area of Joplin, Ottawa Co., Missouri has produced isometric pseudomorphs of Anglesite over Galena, as well as banded Anglesite. This mineral has also come from the Coeur d'Alene District, Kellogg, Shoshone Co., Idaho; the Blanchard Mine, Bingham, Socorro Co., New Mexico; the Mammoth-Saint Anthony Mine, Tiger, Pinal Co., Arizona; and Castle Dome, Yuma Co, Arizona.

Distingushing Similar Minerals

Celestine - Lacks adamantine luster, lighter in weight.
Barite - Lacks adamantine luster.
Cerussite - Effervesces in hydrochloric acid, crystals frequently twinned.
Phosgenite - May be difficult to distinguish, but occurs in different crystals, and is sectile and nonbrittle.


Close

Copyright © 2017. Minerals.net

View on Full Site