Madocite
Encyclopedia
Madocite is a mineral with a general formula of Pb17(Sb,As)16S41. Madocite was named for the locality of discovery, Madoc
, Ontario
, Canada
. It is found in the marbles of the Precambrian
Grenville Limestone. It is orthorhombic (rectangular prism with a rectangular base) and in the point group mm2. Its crystals are elongated and striated along [001] to a size of 1.5 mm.
Madocite is anisotropic and classified as having high relief. It also displays strong pleochroism.
Madocite is found in small clusters in marble
pits (near Madoc, Ontario), and was originally categorized in the 1920s as an unidentified sulfosalt mineral in an assemblage of pyrite
, sphalerite
, and jamesonite
in marble. Later research was done by John L. Jambor in the 1960s who went to the site and collected samples of the assemblages.
Madoc, Ontario
Madoc is a township in Eastern Ontario, Canada, in Hastings County.The township was named after legendary Welsh prince Madoc ap Owain Gwynedd, credited by some with discovering North America in 1170.-Communities:...
, Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. It is found in the marbles of the Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
Grenville Limestone. It is orthorhombic (rectangular prism with a rectangular base) and in the point group mm2. Its crystals are elongated and striated along [001] to a size of 1.5 mm.
Madocite is anisotropic and classified as having high relief. It also displays strong pleochroism.
Madocite is found in small clusters in marble
Marble
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite.Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.Marble is commonly used for...
pits (near Madoc, Ontario), and was originally categorized in the 1920s as an unidentified sulfosalt mineral in an assemblage of pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
, sphalerite
Sphalerite
Sphalerite is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides...
, and jamesonite
Jamesonite
Jamesonite is a sulfosalt mineral, a lead, iron, antimony sulfide with formula Pb4FeSb6S14. With the addition of manganese it forms a series with benavidesite. It is a dark grey metallic mineral which forms acicular prismatic monoclinic crystals. It is soft with a Mohs hardness of 2.5 and has a...
in marble. Later research was done by John L. Jambor in the 1960s who went to the site and collected samples of the assemblages.