Gadolinite, sometimes also known as Ytterbite, is a silicate mineral which consists principally of the silicates of cerium

Cerium

Cerium is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet . Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight...

, lanthanum

Lanthanum

Lanthanum is a chemical element with the symbol La and atomic number 57.Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and...

, neodymium

Neodymium

Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. It is present in significant quantities in the ore minerals monazite and bastnäsite...

, yttrium

Yttrium

Yttrium is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and it has often been classified as a "rare earth element". Yttrium is almost always found combined with the lanthanides in rare earth minerals and is...

, beryllium

Beryllium

Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...

, and iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 with the formula (Ce,La,Nd,Y)₂FeBe₂Si₂O₁₀. It is called gadolinite-(Ce) or gadolinite-(Y) depending on the prominence of the variable element composition (namely, Y if it has more yttrium, and Ce if it has more cerium). It may contain 35.48% yttria sub-group rare earths, 2.17% ceria earths, up to 11.6% BeO and traces of thorium. It is found in Sweden, Norway, and the USA (Texas and Colorado).

Characteristics

Gadolinite is fairly rare and typically occurs as well-formed crystals. It is nearly black in color and has a vitreous luster

Lustre (mineralogy)

Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....

. Its hardness

Mohs scale of mineral hardness

The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in...

 is between 6.5 and 7, and its specific gravity

Specific gravity

Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...

 is between 4.0 and 4.7. It fractures in a conchoidal pattern. The mineral's streak

Streak (mineralogy)

The streak of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a more consistent characteristic color, and is thus...

 is grayish-green. It is also pyrognomic

Pyrognomic

Pyrognomic materials are easily made incandescent. Minerals and metals commonly glow when heated, but those that are pyrognomic glow at much lower temperatures. Allanite and gadolinite are examples of pyrognomic minerals...

, which means that it becomes incandescent

Incandescence

Incandescence is the emission of light from a hot body as a result of its temperature. The term derives from the Latin verb incandescere, to glow white....

 at a relatively low temperature.

Name and discovery

Gadolinite was named in 1800 for Johan Gadolin

Johan Gadolin

Johan Gadolin was a Finnish chemist, physicist and mineralogist. Gadolin discovered the chemical element yttrium...

, the Finnish

Finland

Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...

 mineralogist-chemist who first isolated an oxide of the rare earth element

Rare earth element

As defined by IUPAC, rare earth elements or rare earth metals are a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides plus scandium and yttrium...

 yttrium from the mineral in 1792. The rare earth gadolinium

Gadolinium

Gadolinium is a chemical element with the symbol Gd and atomic number 64. It is a silvery-white, malleable and ductile rare-earth metal. It is found in nature only in combined form. Gadolinium was first detected spectroscopically in 1880 by de Marignac who separated its oxide and is credited with...

 was also named for him. However, gadolinite does not contain more than trace amounts of gadolinium. When Gadolin analyzed this mineral, he missed an opportunity to discover a second element: what he thought was aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 (alumina) was in fact an element that would not be officially discovered until 1798: beryllium

Beryllium

Beryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...

 (beryllia).

Uses

Gadolinite and euxenite

Euxenite

Euxenite or euxenite- is a brownish black mineral with a metallic luster.-Chemistry:It contains calcium, niobium, tantalum, cerium, titanium, yttrium, and typically uranium and thorium, with some other metals. The chemical formula is: 2O6...

 are quite abundant and are future sources of yttrium sub group rare earths. At present, these elements are recovered from monazite

Monazite

Monazite is a reddish-brown phosphate mineral containing rare earth metals. It occurs usually in small isolated crystals. There are actually at least four different kinds of monazite, depending on relative elemental composition of the mineral:...

concentrates (after recovery of ceria sub-group metals).