Corundum is a crystalline form of aluminium oxide typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, padparadscha sapphire, is pink-orange.
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 formula of SiO2. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar.
Spinel is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula MgAl
2O
4 in the cubic crystal system. Its name comes from the Latin word spinella, a diminutive form of spine, in reference to its pointed crystals.
Tourmaline is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. This gemstone comes in a wide variety of colors.
Zircon is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is ZrSiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.
Ulexite (NaCaB5O6(OH)6·5H2O, hydrated sodium calcium borate hydroxide), sometimes known as TV rock or television stone, is a mineral occurring in silky white rounded crystalline masses or in parallel fibers. The natural fibers of ulexite conduct light along their long axes, by internal reflection. Ulexite was named for the German chemist Georg Ludwig Ulex (1811–1883) who first discovered it.
Moissanite is naturally occurring silicon carbide and its various crystalline polymorphs. It has the chemical formula SiC and is a rare mineral, discovered by the French chemist Henri Moissan in 1893. Silicon carbide is useful for commercial and industrial applications due to its hardness, optical properties and thermal conductivity.
Eudialyte, whose name derives from the Greek phrase Εὖ διάλυτος, eu dialytos, meaning "well decomposable", is a somewhat rare, nine member ring cyclosilicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites. Its name alludes to its ready solubility in acid.
Tincalconite is a hydrous sodium borate mineral closely related to borax, and is a secondary mineral that forms as a dehydration product of borax. Its formula is Na2B4O7·5H2O or Na2[B4O5(OH)4]·3H2O.
Seamanite, named for discoverer Arthur E. Seaman, is a rare manganese boron phosphate mineral with formula Mn3[B(OH)4](PO4)(OH)2. The yellow to pink mineral occurs as small, needle-shaped crystals. It was first discovered in 1917 from a mine in Iron County, Michigan, United States and identified in 1930. As of 2012, seamanite is known from four sites in Michigan and South Australia.
The mineral zektzerite is a member of the tuhualite group and was first found in 1966 by Seattle mineralogist Benjamin Bartlett "Bart" Cannon. It was discovered in the Willow creek basin below Silver Star mountain in miarolitic cavities within the alkaline arfvedsonite granite phase of the Golden Horn batholith, Okanogan County, Washington. It is named for Jack Zektzer, mathematician and mineral collector of Seattle, Washington.
Howlite, a calcium borosilicate hydroxide (Ca2B5SiO9(OH)5), is a borate mineral found in evaporite deposits.
Hafnon is a hafnium nesosilicate mineral, chemical formula (Hf,Zr)SiO4 or (Hf,Zr,Th,U,Y)SiO4. In natural zircon ZrSiO4 part of the zirconium is replaced by the very similar hafnium and so natural zircon is never pure ZrSiO4. A zircon with 100% hafnium substitution can be made synthetically and is hafnon.
Jeremejevite is an aluminium borate mineral with variable fluoride and hydroxide ions. Its chemical formula is Al6B5O15(F,OH)3. It is considered as one of the rarest, thus one of the most expensive stones. For nearly a century, it was considered as one of the rarest gemstones in the world.
Karlite (kar'-lite) is a silky white to light green orthorhombic borate mineral, not to be confused with tremolite-actinolite. It has a general formula of Mg7(BO3)3(OH)4Cl. Karlite is named in honor of Franz Karl (1918–1972), professor of mineralogy and petrography at Christian Albrechts University in Kiel, Germany, for his studies of the geology of the eastern Alps.
Panguite is a type of titanium oxide mineral first discovered as an inclusion within the Allende meteorite, and first described in 2012.
Perettiite-(Y) is a complex silicate–borate mineral with the formula Y2Mn4FeSi2B8O24. It was first discovered in 2015 by Adolf Peretti of the Gemresearch Swisslab (GRS). It was found as inclusions in a phenakite crystal from Mogok, Myanmar.
Béhierite is a very rare mineral, a natural tantalum borate of the formula (Ta,Nb)BO4. Béhierite is also one of the most simple tantalum minerals. It contains simple tetrahedral borate anions, instead of more common among minerals, planar BO3 groups. It forms a solid solution with its niobium-analogue, schiavinatoite. Both have zircon-type structure (tetragonal, space group I41/amd) and are found in pegmatites. Béhierite and holtite are minerals with essential tantalum and boron.
Inderite, also known as Lesserite, is a mineral that was named after its source, the Inder lake, near the Inder Mountains in Kazakhstan. The samples were described in English by the soviet mineralogist Boldyreva in 1937. It is a rare secondary mineral but common in salt, potassium and borate deposits.
Takedaite is a borate mineral that was found in a mine in Fuka, Okayama Prefecture Japan during a mineralogical survey in the year 1994. During the survey, Kusachi and Henmi reported the occurrence of an unidentified anhydrous borate mineral closely associated with nifontovite, olshanskyite, and calcite. By the year 1994 two other minerals in the borate group M3B2O6 had been identified in nature Mg3B2O6 known as kotoite and Mn3B2O6 known as jimboite. Takedaite has the ideal chemical formula of Ca3B2O6. The mineral has been approved by the Commission on New Minerals and Mineral Names, IMA, to be named takedaite after Hiroshi Takeda, a professor at the Mineralogical Institute, University of Tokyo Japan.
