 : Rutilated Quartz
Rutilated Quartz used in Jewelry
Source: Occuring worldwide in variant forms
Rutilated Quartz derives its name from the tiny needle-like strands of a material called "rutile" that become imbedded in the quartz crystal, forming fascinating multiple inclusions. The needle-like rutile derives its name from the Latin word "rutilus" or "red," which is used to reference the deep red color that is found in many specimens.
Rutile Composition
Rutile is a crystalized mineral that is composed of titanium dioxide which crystallizes in the tetragonal crystal system, usually forming into a prismatic or twinned configuration. The rutile needles have an "acicular" crystal growth habit.
The rutile needles tend to align with the c axis of the host quartz, and can run the entire length of the crystal. Rutile needles are also associated with other varieties of gemstones such as sapphires and rubies, and the tightly packed clusters of very fine rutile needles present in such gems are responsible for "star" effect which is an optical phenomenon known as asterism.
Rutile is found as an accessory mineral in varieties of altered igneous rock, or within certain varieties of gneisses or schists. When occurring In groupings of acicular crystals, it is frequently seen as an imbedded inclusion within macrocrystalline quartz, commonly known as "rutilated quartz."
Rutilated Quartz Bracelet by Michael Zobel |
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Rutile Sculptures by Atelier Munsteiner |
Rutilated quartz is also known as "Venus' Hairstone," and the hair-like needles within this stone can occur in a variety colors ranging from brown and gold, to red, white, or jet black. Rutile needles are generally less than 1.0mm in diameter. The included rutile needles can occur in evenly aligned sprays, or can be oriented in a randomized pattern.
Some varieties of included needles may have the appearance of titanium dioxide rutile, but are actually comprised of crystalized actinolite, chlorite, and tourmaline.
Quartz
The host quartz is a tectosilicate family of minerals that are typically associated with igneous rock, grown in pegmatites and geodes that formed during the mountain-building process. Quartz crystalizes in the hexagonal/trigonal crystal system (trigonal-trapezohedral).
Quartz has an enantiomorphic and prismatic crystal habit, forming left-right 'Brazil-law' twins (below, center), v-shaped 'Japan-law' twins (below, right), or 'Dauphiné-law' twins of 6-sided prisms; each ending in 6-sided rhombohedron pyramid termination.
Rutilated Quartz Crystallography, Chemistry, Physical Properties
Rutilated Quartz Optical Properties
Fire (Harlequin) Quartz
So-called "fire quartz," or "harlequin quartz" is a mineral variety of clear (transparent) quartz which is flecked with reddish, glitter-like inclusions of lepidocrocite, hematite and and titanium. The principle source for harlequin quartz is Madagascar.
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