Rutilated danburite is a calcium boron silicate mineral. A sorosilicate, with a chemical formula of CaB2(SiO4)2.
Rutilated danburite meaning
It has a Mohs hardness of 7 to 7.5 and a specific gravity of 3.0. The mineral has an orthorhombic crystal form. It is usually colorless, similarly as quartz. But It can also be either pale yellow or also yellowish-brown. It typically occurs in contact metamorphic rocks.
Its name is due to Danbury, Connecticut, United States. Where it was first discovered in 1839 by Charles Upham Shephard.
The Dana classification of minerals categorizes danburite as a sorosilicate. While the Strunz classification scheme lists it as a tectosilicate. Its structure can be interpreted as either.
The mineral occurs with microcline and also oligoclase embedded in dolomite. Large crystals, reaching 10 cm (4 in). In length, We found it with calcite in granite veins at Russell in St Lawrence county, New York. We found smaller nice crystals on gneiss at Mt. Scopi and Petersthal, the valley of the Vals Rhine, in Switzerland. We recently found splendid crystals in Japan.
The clarity, also resilience, and strong dispersion of danburite make it valuable as cut stones for jewelry.
Rutilated danburite needles
Rutile is known for its habit of forming inclusions within other minerals. These needle like inclusions are slender and also long, like straw crystals. Inclusions range from dense parallel fibres to scattered needles within the host mineral. The combination is known to be “rutilate” gemstone.
The word “rutile” describes inclusions in the form of straight lines in gemstones. With time, it became a synonym in the gemstone trade. While most of the time, straight lines are not rutile, but empty tubes coming from crystallization problems of the stone.
When tubes are in the same direction as the axes of the crystalline structure of the stone, in almost all cases, it is not rutile. Unfortunately, many gemologists use the rutile name to facilitate stone denominations because customers would not understand too technical explanations. They use it to buy stones whose names they know. Even if these names are wrong.
Rutilated danburite from Madagascar