加工...

Anatase Gemstone: Properties, Meanings, Value & More

銳鈦礦寶石：屬性、含義、價值等

該文本是機器翻譯的。 顯示原件？

Anatase is a titanium dioxide mineral occasionally used as a gemstone. It comes in an array of deep colors with a diamond-like (adamantine) to somewhat metallic luster.

As a mineral, anatase is relatively rare, but anatase gemstones are even rarer. The stone is more common in mineral collections than jewelry. That said, rare gem-quality anatase crystals make stunning, sparkling faceted stones.

Another popular specimen is anatase on quartz, often forming as small indigo-blue crystals on a large clear quartz crystal.

Ready to learn more? Find out all about anatase gemstone properties, benefits, history, prices, and more in this guide!

About Anatase Stone

Anatase is a semi-precious gemstone found in many colors but usually colorless to blue hues. Another common name for anatase is “octahedrite,” since it commonly forms acute octahedral crystals (resembling a double pyramid). However, anatase crystals aren’t true octahedrons.

Other monikers for anatase are:

• Oisanite

• Dauphinite

• Hydrotitanite

• Wiserine

• Xanthotitane

• Acide titanique

• Schorl bleu indigo

• Schorl octaedre rectanglaire

Some similar-looking gemstones are scapolite and sodalite. An easy way to differentiate these from anatase is that they’re luminescent, while anatase is not.

Astrologically, anatase is a Scorpio stone.

Anatase Uses

Industrially, what is the use of anatase?

For one, anatase is the most common delustrant, a material that reduces the sheen (and often transparency) of synthetic fibers like nylon.

However, the primary industrial application of anatase comes from its photocatalytic effect, so it can absorb photons when exposed to light underwater, exciting its own electrons and causing the electrons to split the water into hydrogen and oxygen. This property is useful in:

• Solar cells

• Air purifiers

• Oil spill cleaning

• Water disinfecting

• Self-cleaning glasses

• Cements

For research into these applications, scientists have created synthetic anatase, but these aren’t sold commercially as a gem.

Scientists have also made synthetic anatase for pigments. What is anatase pigment? Like its sister stone rutile, anatase is crushed into powder for white pigments.

One major difference between anatase vs rutile pigments is that anatase pigment is a brighter white, but rutile is more common and more stable thermodynamically.

Additionally, rutile has a higher density and higher Mohs hardness ranking.

Anatase Specifications & Characteristics

What type of mineral is anatase? Anatase is a titanium dioxide mineral with the formula TiO2. Common impurities are iron, tin, vanadium, and niobium.

There are five natural forms of titanium dioxide, and three are minerals: anatase, rutile, and brookite. The three minerals are polymorphous, meaning their chemical formula is the same but they differ in crystal systems and other properties.

The anatase and rutile crystal structure is tetragonal, but brookite is orthorhombic. Of the three, anatase is the rarest. Brookite has higher density and birefringence.

Most anatase crystals are acute dipyramidal (or pyramidal) and striated. They can also be prismatic or tabular.

The refractive indices of anatase significantly vary based on wavelength and temperature.

Anatase mineral properties listed:

• Mohs hardness: 5.5-6

• Color: Brown, black, light yellow, reddish-brown, blue/indigo, blue-green, light green, lilac, yellowish-brown, gray, colorless; Color-banding common

• Crystal structure: Tetragonal

• Luster: Adamantine, submetallic, or metallic

• Transparency: Transparent to near-opaque

• Refractive index: 2.488-2.564

• Density: 3.79-3.97

• Cleavage: Perfect 2-direction on {001} & {011}

• Fracture: Subconchoidal

• Streak: White to pale yellow

• Luminescence: None

• Pleochroism: Present, usually weak but strong in deep-colored crystals - Brown to yellowish-brown to greenish-blue

• Birefringence: 0.046-0.073

• Dispersion: 0.214 (0); 0.259 (e)

Types of Anatase

Some subtypes of anatase to know are:

• Gel-Anatase: Finely divided variety found in leucoxene pseudomorphs after ilmenite

• Niobium-Bearing Anatase: Variety containing niobium; AKA “niobian anatase” or “anatase-columbite solid solution”

• Xanthitane: Yellow, earthy, soft, and easily crumbled titanite pseudomorph of anatase

Now onto the mystical anatase metaphysical properties!

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Anatase Meaning & History

Metaphysically, anatase is associated with the air element, symbolizing inspiration, intellect, and exploration. The crystal also represents compassion, connection to Earth, and the power of nature.

History

The name “anatase” came from French mineralogist Rene Just Haüy in 1801. What does the name anatase mean? It derives from the Greek term anatasis, meaning “extension,” in reference to these crystals’ pyramidal faces being longer than their base faces, particularly compared to other tetragonal minerals.

The stone’s type locality, where Haüy found his specimens, is the Saint-Christophe-en-Oisans in the Alps of France. This led to the alternate name “oisanite.”

Though anatase pigments weren’t as common in art as, say, rutile pigments, it’s been found as a minor portion of white paints in various ancient artifacts.

Some credit the fascinating optical properties of anatase with the idea to create artificial gems like cubic zirconia in the mid-1900s.

During the early 1900s, scientists started producing synthetic anatase for white paint pigment. However, they struggled to remove iron impurities and stop the anatase from turning to rutile during the process.

The first commercially pure (83 percent TiO2) anatase pigment came from Norway in 1918-1919, but a more popular composite pigment emerged soon after. The composite pigment, described as “old India ivory,” contained calcium phosphate and barium sulfate.

French scientists discovered the Blumenfeld process in 1920, and 96-99 percent titanium dioxide pigment emerged in 1923. Purer anatase pigment had greater “hiding power” (similar to opacity) than the composites. However, rutile had even greater hiding power than anatase, so rutile pigments became more popular.

Pictured above: Anatase crystals on quartz | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Anatase Healing Properties

As a healing stone, anatase is well-known in its indigo-blue form, joining other blue gemstones in enhancing communication, wisdom, and tranquility. Blue gems are also chakra stones for the throat and third eye chakras.

Physical Healing

Physically, anatase is said to treat:

• Sinus issues

• Allergies

• Bone fractures

• Tooth cavities

• Effects of aging on skin

• Slow metabolism

Emotional Healing

Emotionally, anatase gems are believed to improve or boost:

• Communication

• Relationship satisfaction

• Open-mindedness

• Feelings of empathy

• Problem-solving capabilities

What about anatase’s value as a gemstone?

Image credit: Carles Millan | Creative Commons Attribution 3.0 Unported license

Anatase Gemstone Properties

Besides its rarity, the factors that determine anatase value include color, cut, clarity, transparency, and carat weight.

Color

Anatase comes in many colors, but most collectors know it in shades of blue to green or reddish-brown. Growth zoning often leads to color-banding.

Compared to other titanium oxide minerals, anatase color is commonly darker because of magnesium or iron impurities.

Though the refractive indices and dispersion of the stone are high, which could allow for great sparkle, deeper colors make the stone appear more opaque.

Cut

Most anatase crystals are quite small, and this combined with their perfect cleavage means they’re rarely faceted. Any faceted anatase gems are more valuable.

Anatase on quartz may be cut into cabochons, faceted, carved, or sold uncut (rough).

Clarity & Transparency

Clarity isn’t a major factor for anatase value, given the rarity of transparent crystals. Most anatase crystals have visible inclusions and blemishes like cracks or formation defects. Anatase is often an inclusion in quartz, often beside chlorite, rutile, and/or clay minerals.

Light-colored anatase is more often transparent than deep-colored anatase, which leans toward opaque. Pyramidal crystals can also look opaque because of “total internal reflection,” a phenomenon where the light entering the gem reflects internally instead of exiting.

Faceted transparent anatase gems can display birefringent doubling, meaning the facets on the opposite side of the stone will look doubled.

Carat Weight & Size

Faceted anatase gems are usually 1-2 carats or lower, though some have reached 6 carats. Raw anatase crystals are typically under 10 mm, and large rhomboid anatase crystals are highly sought-after.

Image credit: Christian Rewitzer | Creative Commons Attribution 3.0 Unported license

Anatase Formation & Sources

Anatase crystals can form in igneous rocks, but it’s usually formed as a secondary mineral when titanium-bearing minerals undergo weathering or hydrothermal alteration.

What type of rock is anatase found in? Anatase can be found in igneous and metamorphic rocks like

• Schists

• Gneisses

• Granites

• Syenites

• Pegmatites

• Carbonatites

You can also find anatase as detritus in sediments and placer deposits.

Mining Locations

Where is anatase found in the world? Gem-quality anatase crystals are primarily sourced from the Swiss Alps and diamond-containing gravels in Brazil.

Other notable sources:

• France

• Italy

• Myanmar

• Norway

• Pakistan

• Russia

• Spain

• UK (Cornwall, England, Wales)

• USA (Arkansas, California, Colorado, Massachusetts, North Carolina, Virginia)

Now, how much does anatase cost?

Image credit: Christian Rewitzer | Creative Commons Attribution 3.0 Unported license

Anatase Price & Value

The cost of anatase depends on the cut, size, and quality of the piece along with the seller.

Small, dark-colored, faceted anatase gems with visible blemishes are typically $40-$90 per carat or around $20-$30 each, since they’re usually under 1 carat.

Higher-quality faceted anatase gems in large sizes can go for $90-$975 per carat.

Attractive anatase crystals (uncut) vary from around $25 to $250 to $2,500 each.

Anatase Care and Maintenance

Lastly, we’ll discuss gemstone care. If you find anatase jewelry, be sure it has protective settings.

Clean anatase with a soft toothbrush, warm water, and mild soap. Store it separately from other gems to avoid scratches.

Show Your Classy Taste with Anatase!

Anatase is a diverse crystal in both color and industrial applications. Lighter colored stones offer more transparency while darker colored stones offer greater luster, so there’s a great option for any taste!

Buy anatase and other unique gemstones today!