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Chemical Formula | Pb5(AsO4)3Cl | ||
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Composition | Lead chloro-arsenate. The arsenate radical (AsO4) may be partially replaced by a phosphate radical (PO4), or a vanadate radical (VO4), thus forming a series with Pyromorphite and Vanadinite. | ||
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Variable Formula | Pb5([As,P]O4)3Cl
; Pb5([As,V]O4)3Cl |
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Color | Yellow, orange, orange-yellow, brown, pale yellow. Rarely colorless or white. | ||
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Streak | White | ||
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Hardness | 3½ - 4 | ||
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Crystal Forms and Aggregates |
(Hexagonal) Occurs in small, slender, prismatic crystals and in mammilary crusts. A very rare habit is large, stubby, hexagonal crystals. Also occurs as wedge-shaped crystals, acicular, radiating, botryoidal, reniform, encrusting, and in curvy aggregates. Larger crystals may be hollowed out on the ends. | ||
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Transparency | Transparent to translucent | ||
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Specific Gravity | 7.0 - 7.3 | ||
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Luster | Resinous | ||
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Cleavage | Indiscernible | ||
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Fracture | Subconchoidal to uneven | ||
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Tenacity | Brittle | ||
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Varieties |  Campylite - Wedge-shaped,
orange-yellow to brown variety with curved faces |
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Polymorphs | Clinomimetite - Rare, monoclinic form of Mimetite | ||
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In Group | Phosphates ; Arsenates ; Apatite group | ||
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All About | Mimetite is a member of the Apatite group, a group of isomorphous hexagonal minerals. It is very similar in structure and appearance to Pyromorphite, and may be partially replaced by it. The intermediary member between Mimetite and Pyromorphite is called "Pyromorphite-Mimetite". Mimetite is also structurally similar to Vanadinite, and may also be partially replaced by it. The intermediary member between Mimetite and Vanadinite is "Endlichite". | ||
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Uses | Mimetite is a minor ore of lead where it occurs with more abundant lead minerals. It is also a popular mineral among collectors. | ||
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Striking Features | Color, crystal habits, mineral associates, and occurrences | ||
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Complex Tests | 1) Dissolves in hydrochloric acid 2) Gives off a strong garlic odor if heated (Warning: fumes are poisonous!) |
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Popularity (1-4) | 2 | ||
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Prevalence (1-3) | 3 | ||
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Demand (1-3) | 1 | ||
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Distinguishing Similar Minerals |
Pyromorphite - Usually greener in color, and
occurs in hollow crystals. Otherwise cannot be
distinguished with practical methods. Vanadinite - Usually redder in color, has a slightly yellow streak, and is slightly softer. Otherwise cannot be distinguished with practical methods. Apatite - Harder (5) |
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Commonly Occurs With |
Wulfenite, Vanadinite, Limonite, Galena, Barite, Anglesite, Hemimorphite, Arsenopyrite | ||
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Noteworthy Localities |
Mimetite is a rare mineral, and only few
localities produce good specimens. Transparent, prismatic crystals and aggregates occur in Tsumeb,
Namibia. Very large, yellow to nearly colorless crystals
were found in Johanngeorgenstadt, Saxony, Germany. Nearly
colorless crystals were also found in Pribam, Czech
Republic. Long, spear-like crystals, as well as the
variety Campylite, are famous from the mines of
Caldbeck Fells, Cumbria, England. Large crystals and
clusters are found on Mount Bonnie, Northern Territory,
Australia. In Mexico, globular blobs and encrustations of yellow Mimetite occur with Wulfenite in San Pedro Corralitos, Durango. Orange radial encrustions occur in Cerro Prieta, Sonora, also associated with Wulfenite. Also famous in Mexico is Santa Eulalia, Chihuahua. In the U.S., small blobs and encrustations occur in the No. 79 Mine, Hayden, Gila Co., Arizona; the Rowley Mine, near Theba, Maricopa Co., Arizona; and in the Wheatly Mines, Phoenixville, Chester Co., Pennsylvania. |
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Picture Icon Links |
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Picture Links | 1. Mimetite blobs with Wulfenite |
