THE MINERAL ANATASE
- Chemical Formula: TiO2, Titanium Oxide
- Class: Oxides and Hydroxides
- Uses: A very minor ore of titanium and as mineral specimens.
Specimens
Anatase and rutile have the same symmetry, tetragonal 4/m 2/m 2/m, despite having different structures. In Rutile, the structure is based on octahedrons of titanium oxide which share two edges of the octahedron with other octahedrons and form chains. It is the chains themselves which are arranged into a four-fold symmetry. In anatase, the octahedrons share four edges hence the four fold axis.
Crystals of anatase are very distinctive and are not easily confused with any other mineral. They form the eight faced tetragonal dipyramids that come to sharp elongated points. The elongation is pronounced enough to distinguish this crystal form from octahedral crystals, but there is a similarity. In fact anatase is wrongly called "octahedrite" in spite of the difference in forms. Of course "tetragonal dipyramidite" does not sound right either!
Nice specimens of anatase are associated with quartz and are considered classics in the mineral world. The good luster, well formed crystal shape and interesting character make anatase a popular mineral for collectors.
PHYSICAL CHARACTERISTICS:
- Color is brown to black, also yellow and blue.
- Luster is adamantine to submetallic.
- Transparency crystals are opaque.
- Crystal System is tetragonal; 4/m 2/m 2/m
- Crystal Habits include the typical tetragonal dipyramids that come to sharp elongated terminations points. These crystals look like stretched out octahedrons.
- Cleavage is perfect in the basal direction and in four directions, pyramidal.
- Fracture is subconchoidal.
- Hardness is 5.5 - 6
- Specific Gravity is 3.8 - 3.9 (average for metallic minerals)
- Streak is white.
- Other Characteristics: Crystals are easily altered in nature and sometimes pitted.
- Associated Minerals include brookite, rutile, quartz, feldspars, apatite, hematite, chlorite, micas, calcite and sphene.
- Notable Occurrences include Somerville, Massachusetts and Gunnison Co., Colorado, USA; Tavistock, Devon, England; Austria; Diamantina District, Brazil; in the French Alps and at the Binnatal area of Switzerland.
- Best Field Indicators are crystal habit, luster, cleavage, density, streak, associations and locality.
 Amethyst Galleries' Mineral Gallery MINERALS |
ANATASE specimen ase-1
$ 25.00
$ 25.00
Dims: 0.6" x 0.2" x 0.5"(1.5 x 0.5 x 0.5 cm)
Wt: 0.7 g
Hadagavida, Norway
I haven't seen too many specimens from Norway in my travels, and even fewer specimens of Anatase, but here's one. It occurs in the tetragonal dipyramidal form that resembles an octahedron that was stretched along one axis. Its form is exceptional, with no damage and clean, distinct faces and edges that have a smattering of microscopic crystals on them that could be either muscovite, chlorite, or even tiny Anatases; they are too small for me to tell. The crystal shows heavy striations that run perpendicular to its long axis, has a black color, a submetallic luster, and is opaque. It is a really splendid thumbnail specimen that I put into a domed, plastic thimble box for display and protection.
ase-1 ($ 25.00)
Hadagavida, Norway
ANATASE specimen ase-2$ 80.00
Dims: 1.0" x 0.4" x 0.5"(2.5 x 1.0 x 1.3 cm)
Wt: 4.2 g
Hadagavida, Norway
This excellent thumbnail specimen consists of 6 small, tetragonal bipyramidal Anatase crystals growing off of a much larger one in the same form. All show no visible damage and have clean edges and striated faces that are dusted with microscopic crystals of an unknown mineral(maybe muscovite, chlorite, or more Anatase). Their color is black, they have a metallic luster, and they are opaque. I have not seen such excellence in crystal form in a while- this is a near-perfect specimen. I have affixed it into a plastic thimble box for display and protection- it looked as if it needed a "house".
ase-2 ($ 80.00)Hadagavida, Norway
ANATASE specimen ase-3
$ 150.00
$ 150.00
Dims: 1.0" x 0.4" x 0.3"(2.5 x 1.0 x 0.8 cm)
Wt: 2.7 g
Hadagavida, Norway
This small thumbnail specimen consists of a single tetragonal bipyramidal Anatase crystal. It shows noticeable damage to the area where the two pyramids meet that is likely due to the crystal's separation from its place of origin, and the very tip of one termination is missing. However, its form is excellent, possessing sharp edges and faces that show an adamantine luster which is slightly metallic; the faces are all dusted with microscopic crystals of muscovite or chlorite, some more heavily than others. It has a black coloration and is completely opaque. There is no host rock of any sort attached to the crystal.
ase-3 ($150.00)
Hadagavida, Norway
ANATASE specimen ase-4
$ 40.00
$ 40.00
Dims: 0.6" x 0.2" x 0.2"(1.5 x 0.5 x 0.5 cm)
Wt: 0.7 g
Hadagavida, Odda, Hordaland County, Norway
This small specimen consists of a single tetragonal dipyramidal Anatase crystal. It is in good condition, though both of its termination tips are slightly chipped, and it has excellent form, with well-defined edges and clean faces that possess a bright metallic-to-adamantine luster. Its color is black and it is essentially opaque. Portions of each of its sides are lightly dusted with tiny muscovite or chlorite crystals, but these are not very noticeable.
ase-4 ($ 40.00)
Hadagavida, Odda, Hordaland County, Norway
ANATASE specimen ase-5
$ 45.00
$ 45.00
Dims: 0.5 x 0.2 x 0.2" (1.3 x 0.5 x 0.5 cm)
Wt: 0.5 g
Hadagavida, Odda, Hordaland County, Norway
This small thumbnail specimen consists of two partly intergrown Anatase crystals- the larger has dimensions of 0.5 x 0.2 x 0.2" (1.3 x 0.5 x 0.5 cm), and the smaller measures 0.3 x 0.1 x 0.1" (8 x 3 x 2 cm). Both are in excellent condition, showing only very slight damage at their tips, and have excellent tetragonal dipyramidal form, with well-defined edges and relatively clean faces that possess a bright submetallic luster. The crystals have a gray-black coloration and are thoroughly opaque. Their sides are ligthly dusted with partly-intergrown chlorite crystals that are almost microscopic in size, and there is no host rock present.
ase-5 ($ 45.00)
Hadagavida, Odda, Hordaland County, Norway
ANATASE specimen ase-6
$ 45.00
$ 45.00
Dims: 0.5 x 0.2 x 0.2" (1.3 x 0.5 x 0.5 cm)
Wt: 9.0 g w/ specimen box
Hadagavida, Odda, Hordaland County, Norway
Two small Anatase crystals make up this tiny thumbnail specimen. One of these makes up most of the dimensions of the entire specimen, whereas the other is much smaller. Both are in excellent condition and have excellent tetragonal bipyramidal form, with sharp edges and relatively clean faces that possess a bright, almost metallic luster. Both are colored black and are opaqe, and show many tiny crystals of either chlorite or more Anatase partly intergrown on their surfaces. There is no host rock present, and the piece is affixed inside a specimen box with an adhesive putty.
ase-6 ($ 45.00)
Hadagavida, Odda, Hordaland County, Norway
ANATASE specimen ase-7
$ 45.00
$ 45.00
Dims: 2.57x2.27x1.58" (6.52x5.78x4.01cm)
Wt: 4.41oz (126.0g)
Corral Canyon, Dixie Valley, Nevada, USA
This specimen contains the mineral anatase in two different forms. First of all, most of the anatase appears massive (at least externally), as opaque, dull brown pseudomorphs after titanite (sphene). The rest of the anatase is in the form of perfect little transparent brown tetragonal dipyramid crystals (elongated octahedrons, for those that have not read our description of anatase!).
ase-7 ($ 45.00)
Corral Canyon, Dixie Valley, Nevada, USA