Malayaite is a

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

silicate mineral Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...

with formula CaSnOSiO₄. It is a member of the

titanite Titanite, or sphene (from the Greek ''sphenos'' (σφηνώ), meaning wedge), is a calcium titanium nesosilicate mineral, Ca Ti Si O5. Trace impurities of iron and aluminium are typically present. Also commonly present are rare earth metals ...

group.

Discovery

Malayaite was originally found in Perak (a state in Malaysia) and was first described in literature in 1961, though it was not yet given a name. In 1965, the mineral was named and recognized by the International Mineralogical Association. It was named for the locality in which it was discovered; which is the Malay Peninsula in

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Crystal structure and symmetry

This mineral is classified under the nesosilicate group for

silicate minerals Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually con ...

because the titanite group falls under this category as well. Minerals in the nesosilicate group have isolated SiO₄ tetrahedra connected to cations. In malayaite, the

tetrahedra 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 ...

are connected to the chain of distorted SnO₆

octahedra In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...

, in which the octahedra are linked by vertex 'trans'' cornerssharing and form chains parallel to the

miller index Miller indices form a notation system in crystallography for lattice planes in crystal (Bravais) lattices. In particular, a family of lattice planes of a given (direct) Bravais lattice is determined by three integers ''h'', ''k'', and ''� ...

of 00 Within the SnO₆-SiO₄ framework, the CaO₇

polyhedra In geometry, a polyhedron (plural polyhedra or polyhedrons; ) is a three-dimensional shape with flat polygonal faces, straight edges and sharp corners or vertices. A convex polyhedron is the convex hull of finitely many points, not all on ...

form chains parallel to 01 Malayaite belongs to the

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystal system In crystallography, a crystal system is a set of point groups (a group of geometric symmetries with at least one fixed point). A lattice system is a set of Bravais lattices. Space groups are classified into crystal systems according to their poin ...

and has a 2/m (prismatic) crystal class. According to the

Hermann–Mauguin notation In geometry, Hermann–Mauguin notation is used to represent the symmetry elements in point groups, plane groups and space groups. It is named after the German crystallographer Carl Hermann (who introduced it in 1928) and the French mineralogis ...

, the '2' refers to the two-fold axis while the 'm' refers to the presence of a single mirror plane. The '/' symbol indicates that the twofold axis is perpendicular to the mirror plane. The

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

for malayaite is A2/a. According to the

Bravais lattice In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by : \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n ...

symbol, 'A' refers to single face centering of the motif. This means that there is one more point on the center of one face. '2' refers to the two-fold rotation axis while the '/' indicates that a mirror plane is perpendicular to the ''a''-axis, which is the last symbol on that space group notation.

Optical properties

Malayaite exhibits

anisotropy Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physic ...

so it is doubly refractive and breaks up the light that travels through it into two distinct rays of different speeds. This mineral is known to have very high optical relief and has three indices of refraction. Since it is a monoclinic mineral, Malayaite exhibits two different colors under

plane polarized light Polarization ( also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of th ...

making it a

pleochroic Pleochroism (from Greek πλέων, ''pléōn'', "more" and χρῶμα, ''khrôma'', "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light. Backgroun ...

mineral. Malayaite is biaxial

birefringent Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefring ...

(trirefringent).

Functions and purposes

Malayaite has excellent thermal properties and stability making its host lattice ideal for ceramic pigmentation unlike its analogous mineral,

that undergoes phase transition at a higher temperature. This makes chromium-doped malayaite very desirable as it provides a consistent pigment for ceramics. Malayaite contains the element

which is sometimes doped with chromium or

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

. These chromophore elements allows the mineral to produce different pigmentation. If malayaite is chromium-doped, it produces a pink-red color while with nickel, it produces a purple color. Pink chromium-doped malayaite {{chem2, Ca(Sn,Cr)SiO5 is among a few important minerals used in producing pigments for the ceramic industry, specifically for coloring glazes as it produces a resilient color.Costa, G., Ribeiro, M.J., Labrincha, J.A., Dondi, M., Matteucci, F and Crucian, G. (2008) Malayaite ceramic pigments prepared with galvanic sludge. Dyes and Pigments, 78, 2, 157-164.

Occurrence

This mineral is generally found in tin-rich contact metamorphic

skarn Skarns or tactites are hard, coarse-grained metamorphic rocks that form by a process called metasomatism. Skarns tend to be rich in calcium-magnesium-iron-manganese-aluminium silicate minerals, which are also referred to as calc-silicate mineral ...

deposits. There is a possibility that malayaite is a hydrothermal altered form of cassiterite-

quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...

assemblage or some tin-bearing mineral. There have been specimens that were found with malayaite as a coating mineral on cassiterite.

References

Nesosilicates Tin minerals Monoclinic minerals Minerals in space group 15