A cluster of spherical masses of Mimetite from Mexico.
Mimetite with Calcite
from Mexico
Specimen from
the Arizona Mining and Mineral Museum Collection # MM-0784.
A single,
tabular crystal of Mimetite.
Mimetite crystals on Limonite from Australia.
CHEMISTRY Pb5(AsO4)3Cl
CRYSTALLOGRAPHY Hexagonal
CRYSTAL GROWTH AND HABITS Prismatic acicular is the most common growth form for Mimetite although it also occurs as tabular crystals. It is usually found in rounded or mammilary masses and also as stalactitic growths or granular.
COLOR AND OTHER OPTICAL PROPERTIES Pale to bright yellow, yellowish brown to yellowish orange and white, translucent to opaque
HARDNESS 3.5 - 4
SPECIFIC GRAVITY 7.24
LUSTER Vitreous
STREAK White
BREAKABILITY Mimetite displays an imperfect cleavage in 1 direction and has an uneven to subconchoidal fracture. It is brittle.
OCCURRENCE Mimetite is a secondary mineral found in the oxidized zone of arsenic and lead deposits.
ASSOCIATED MINERALS Cerussite, Anglesite, Wulfenite, Barite, Pyromorphite.
OTHER INFORMATION Mimetite was named from the Greek for imitator because it mimics Pyromorphite.