Mimetite Value, Price, and Jewelry Information


MIMETITE: Tsumeb, Namibia (2.81). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Faceted mimetite is one of the rarest of all gems since only one pocket of transparent crystals has ever been found (at Tsumeb), and few of these crystals have been cut. Orange and yellow cabochons are richly colored but are too soft for wear.

Mimetite Value

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Mimetite Information

DataValue
NameMimetite
Crystallography Monoclinic (pseudo-hexagonal). Crystals acicular; globular; botryoidal.
Colors Sulfur yellow, yellowish brown, orange-yellow, orange, white, colorless.
Luster Subadamantine to resinous.
Fracture Subconchoidal to uneven; brittle.
Hardness 3.5-4.
Specific Gravity 7.24. lower if Ca replaces Pb.
Birefringence 0.019.
Cleavage None.
Stone SizesCabochons up to an inch or two can be cut from globular orange and yellow masses from Mexico, and these make unusual and interesting stones. Tsumeb crystals are extremely rare (one pocket found), and most of the crystals are being preserved as specimens and will not be cut. Small broken crystals were cut, yielding some stones up to a few carats in weight, with a maximum of 5-7 carats.
Luminescence Orange-red in LW (Tsumeb, Namibia).
Spectral Not diagnostic.
FormulaPb5(AsO4)3Cl.
Pleochroism Weak in yellow shades.

Apatite Group, Pyromorphite series.

Optics: o = 2.147; e= 2.128.

Biaxial (—); may sometimes be uniaxial.

Occurrence: A secondary mineral in the oxidized zone of lead deposits.

Pennsylvania.

Scotland; Sweden; France; Germany; USSR; Czechoslovakia; Australia.

Southwestern United States: many localities.

Chihuahua, Mexico: fine globular orange and yellow masses.

Mapimi, Durango, Mexico: yellowish globular masses.

Cornwall and Cumberland, England: a variety called campylite.

Tsumeb, Namibia: fine yellow transparent crystals, up to 1 inch long.

Comments: Faceted mimetite is one of the rarest of all gems since only one pocket of transparent crystals has ever been found (at Tsumeb), and few of these crystals have been cut. Orange and yellow cabochons are richly colored but are too soft for wear.

Name: From a Greek word meaning imitator, because of the resemblance to pyromorphite.