Yangite (PbMnSi₃O₈·H₂O) is a chain-silicate mineral, first discovered within the Kombat mine in

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

. The mineral is named after Hexiong Yang, a researcher at the

University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a public land-grant research university in Tucson, Arizona. Founded in 1885 by the 13th Arizona Territorial Legislature, it was the first university in the Arizona Territory. T ...

's Department of Geosciences. Yangite was approved as a valid mineral species by the

International Mineralogical Association Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. Th ...

in 2012.

Occurrence

Yangite was initially found within a specimen taken from the Kombat mine, located in the Otavi Valley, Namibia. The specimen was obtained from John Innes, a senior mineralogist of the Tsumeb Corporation. Yangite occurs in an ore defined as an

epithermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

association. This ore type forms with narrow veins composed of

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cryst ...

rhodochrosite Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO3. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. It streaks white, and its Mohs hardness varies bet ...

, helvite, and

barite Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

Physical Properties

Yangite is colorless, ranging to pale brown when exposed to transmitted light. The mineral has a

vitreous luster Lustre (British English) or luster (American English; see spelling differences) is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin ''lux'', meaning "light", and generally imp ...

and streaks white. Yangite maintains a Mohs hardness of five, and demonstrates perfect cleavage along . There is no evidence of twinning or parting within the available specimens. Yangite is

sectile Sectility is the ability of a mineral to be cut into thin pieces with a knife. Minerals that are not sectile will be broken into rougher pieces when cut. Metals and paper are sectile. Sectility can be used to distinguish minerals of similar appea ...

, commonly found with bladed or platy habit. The mineral is

biaxial In crystal optics, the index ellipsoid (also known as the ''optical indicatrix'' or sometimes as the ''dielectric ellipsoid'') is a geometric construction which concisely represents the refractive indices and associated polariz ...

, elongated up to 12 mm in length along the 10axis. Yangite is insoluble in several fluids, including water,

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

, and

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid Acid strength is the tendency of an acid, symbol ...

Chemical composition

Yangite has a consistent chemical composition, determined using a CAMECA SX100 electron

microprobe A microprobe is an instrument that applies a stable and well-focused beam of charged particles (electrons or ions) to a sample. Types When the primary beam consists of accelerated electrons, the probe is termed an electron microprobe, when the prim ...

. Additionally, the presence of H₂O was confirmed using structural determination and Raman spectroscopic measurements. Elemental Weight Percent:

X-ray crystallography

Yangite was analyzed by both powder and single-crystal X-ray diffraction. Data was collected using the

Bruker Bruker Corporation is an American manufacturer of scientific instruments for molecular and materials research, as well as for industrial and applied analysis. It is headquartered in Billerica, Massachusetts, and is the publicly traded parent compa ...

X8 APEX2 CCD

diffractometer A diffractometer is a measuring instrument for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles (such as X-rays or neutrons) interacts with it. Principle Because it is relatively eas ...

. The diffraction data was influenced by severe peak overlap, leading to uncertainty in the resulting index. Powder Diffraction Data:

Crystal structure

The chain silicate structure is formed by double

wollastonite Wollastonite is a calcium inosilicate mineral ( Ca Si O3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature a ...

chains. These

tetrahedral In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...

formations run parallel with the 10axis and connect with Mn-polyhedra and Pb-polyhedra at the corners. The chains are also defined by four-membered and six-membered alternating tetrahedral rings. Yangite has three Si tetrahedral sites, defined as Si1, Si2, and Si3. Respectively, the average bond lengths are 1.622 Å, 1.622 Å, and 1.624 Å. Yangite is composed of an octahedrally coordinated Mn²⁺ cation. Within the crystal structure, Pb²⁺ has a coordination number of five, bonded with O molecules.

References