Malayaite
Encyclopedia
Malayaite is a calcium
tin
silicate mineral with formula CaSnO[SiO4]. It is a member of the titanite
group.
(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.
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 are connected to the chain of distorted SnO6 octahedra, in which the octahedra are linked by vertex [trans corners] sharing and form chains parallel to the miller index
of [100]. Within the SnO6-SiO4 framework, the CaO7 polyhedra form chains parallel to [101].
Malayaite belongs to the monoclinic crystal system
and has a 2/m (prismatic) crystal class. According to the Hermann–Mauguin notation, 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 two fold axis is perpendicular to the mirror plane.
The space group
for malayaite is A2/a. According to the Bravais lattice 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.
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 making it a pleochroic mineral. Malayaite is biaxial birefringent (trirefringent).
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 tin
which is sometimes doped with chromium
or nickel
. 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 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.
deposits. There is a possibility that malayaite is a hydrothermal altered form of cassiterite
-quartz
assemblage or some tin-bearing mineral. There have been specimens that were found with malayaite as a coating mineral on cassiterite.
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
silicate mineral with formula CaSnO[SiO4]. It is a member of the titanite
Titanite
Titanite, or sphene , is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present...
group.
Discovery
Malayaite was originally found in PerakPerak
Perak , one of the 13 states of Malaysia, is the second largest state in the Peninsular Malaysia bordering Kedah and Yala Province of Thailand to the north, Penang to the northwest, Kelantan and Pahang to the east, Selangor the Strait of Malacca to the south and west.Perak means silver in Malay...
(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
International Mineralogical Association
The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 plus known mineral species...
. It was named for the locality in which it was discovered; which is the Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...
in Malaysia.
Crystal structure and symmetry
This mineral is classified under the nesosilicate group for silicate mineralsSilicate minerals
The silicate minerals make up the largest and most important class of rock-forming minerals, constituting approximately 90 percent of the crust of the Earth. They are classified based on the structure of their silicate group...
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 are connected to the chain of distorted SnO6 octahedra, in which the octahedra are linked by vertex [trans corners] sharing and form chains parallel to the miller index
Miller index
Miller indices form a notation system in crystallography for planes and directions in crystal lattices.In particular, a family of lattice planes is determined by three integers h, k, and ℓ, the Miller indices. They are written , and each index denotes a plane orthogonal to a direction in the...
of [100]. Within the SnO6-SiO4 framework, the CaO7 polyhedra form chains parallel to [101].
Malayaite belongs to the monoclinic crystal system
Crystal system
In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals...
and has a 2/m (prismatic) crystal class. According to the Hermann–Mauguin notation, 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 two fold axis is perpendicular to the mirror plane.
The space group
Space group
In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...
for malayaite is A2/a. According to the Bravais lattice 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 anisotropyAnisotropy
Anisotropy is the property of being directionally dependent, as opposed to isotropy, which implies identical properties in all directions. It can be defined as a difference, when measured along different axes, in a material's physical or mechanical properties An example of anisotropy is the light...
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
Optical relief
Optical relief is a concept in optical mineralogy which refers to the degree in which mineral grains stand out from the mounting medium, usually either oil with a known refractive index or Canada Balsam...
and has three indices of refraction. Since it is a monoclinic mineral, Malayaite exhibits two different colors under plane polarized light making it a pleochroic mineral. Malayaite is biaxial birefringent (trirefringent).
Functions and purposes
Malayaite has excellent thermal properties and stability making its host lattice ideal for ceramic pigmentation unlike its analogous mineral, titaniteTitanite
Titanite, or sphene , is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present...
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 tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
which is sometimes doped with chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
or nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
. These chromophore
Chromophore
A chromophore is the part of a molecule responsible for its color. The color arises when a molecule absorbs certain wavelengths of visible light and transmits or reflects others. The chromophore is a region in the molecule where the energy difference between two different molecular orbitals falls...
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 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.
Occurrence
This mineral is generally found in tin-rich contact metamorphic skarnSkarn
Skarn is an old Swedish mining term originally used to describe a type of silicate gangue, or waste rock, associated with iron-ore bearing sulfide deposits apparently replacing Archean age limestones in Sweden's Persberg mining district. In modern usage the term "skarn" has been expanded to refer...
deposits. There is a possibility that malayaite is a hydrothermal altered form of cassiterite
Cassiterite
Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem...
-quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
assemblage or some tin-bearing mineral. There have been specimens that were found with malayaite as a coating mineral on cassiterite.