Thulite is the translucent to opaque pink variety of zoisite, which is often mottled or streaked with gray or white quartz. The name thulite is derived from its discovery location, Norway, which was once called Thule. This gem is also called rosaline. Thulite is often cut en cabochon for jewelry manufacture or carved into ornaments.
Tiger iron is a rock that is made up of tiger's eye quartz, black hematite and red jasper. These minerals create contrasting bands of color for a truly unique look popularly used for many sorts of ornamentation and decoration.
Tiger's eye is a unique and mysterious member of the quartz family. It ranges in color from rich, golden yellow to bronze and brown. Best seen when gems are cut en cabochon, tiger's eye displays an optical phenomenon known as chatoyancy. Unlike other chatoyant gems, tiger’s eye quartz is made up of quartz with intergrown fibers of amphibole that were altered to golden or rusty-brown limonite. When light hits the surface of this gem, a silky, wavy shimmer moves across the surface of the stone resembling the eye of a tiger. A related variety of quartz called hawk’s eye is blue due to unaltered inclusions of crocidolite.
Titanite gets its name from the titanium in its chemical makeup. Gem quality material is known as sphene. The crystals form as wedge shapes and twinning is common. The color can range from yellow to red, brown, brownish, or yellowish green to green, and black. Specimens can have adamantine luster and high dispersion. Titanite has a high birefringence.
Topaz can be both very common (when clear, or in certain colors like brown, which can turn blue when treated) and very rare (when found in natural beautiful colors rare to the species, like pink and red). Topaz's popularity stems from the gem's good wearability and affordability. Topaz is also often altered with special surface treatments to give it unusual colors and iridescent effects, like mystic, ocean, kiwi, and orchid topaz. Topaz is also a popular birthstone, as blue topaz is December's primary birthstone and yellow topaz is a birthstone for November.
Topazolite is an Andradite Garnet that is yellow or brownish in color. It has a similar appearance to Topaz, and this resemblance inspired its name.
Mother Nature must have been in a whimsical, artistic mood when she created tourmalinated quartz. These crystals are usually colorless rock crystal with long, slender tourmaline inclusions, usually black in color. A relative unknown to the general public, this gem is truly a marvel! The inclusions are always one-of-a-kind, making a beautiful display in a gem collection or jewelry pieces.
Once proposed to be the national gemstone of the United States, tourmaline is found all over the world and in a variety of colors. Tourmaline is the most colorful of all gemstones because, according to an ancient Egyptian legend, it passed through a rainbow on its journey to Earth and brought all of the colors of the rainbow with it. Tourmaline is a mineral group comprised of multiple species of complex borosilicates. Lovingly referred to by mineralogists as the garbage can mineral, its crystal structure allows for the incorporation of a wide range of elements, many of which cause the stunning color varieties and spectacular zoning of tourmaline, including copper, manganese, iron, and titanium. Major tourmaline species include liddicoatite, dravite, uvite, schorl, and elbaite.
Deriving its name from a locality in the Swiss Alps, tremolite is a member of the amphibole group, a complex series of silicate minerals. It forms in thin, parallel fibers, sometimes producing a distinct cat's eye effect when cut in cabochons. Tremolite comes in a variety of colors ranging from white, brown, colorless, gray, light green, light yellow and pink-violet. This gem sometimes occurs as fine, needle-like inclusions in emerald and quartz.
Trilobites are remarkable, hard-shelled creatures that lived some 400 to 500 million years ago in Earth's ancient seas. Trilobites represent the single most diverse class of extinct organisms. Throughout the 270 million years they inhabited the oceans, they continued to evolve into various species, leading to a great deal of diversity in their size, form and function. This means there is a wide variety of trilobite fossils to collect! One of the most appealing factors about trilobite fossils is that you can hold and examine an entire fossil animal as you turn it about in your hand.
The term triphane originated as another name for spodumene, but more recently has been used in reference to colorless to light yellow transparent spodumene. Triphane's name is derived from a Greek term meaning 'three aspects', due to its distinctive trichroism.
Triplite is named for its three cleavage planes that are oriented at right angles to each other. The structure of this stone, combined with its brittle nature, makes faceting very difficult. Successfully faceted triplite gems are coveted by collectors.
Tsavorite is one of two green varieties of garnet, though arguably the more important of the two. Especially in smaller sizes, tsavorite creates competition for emerald because it is less included, rarely treated and more durable. Like some emerald and green tourmaline, tsavorite garnet owes its green hues to the presence of vanadium and chromium. First discovered in Tanzania in 1967 and a few years later in Kenya, tsavorite's name pays homage to the nearby Tsavo National Park.
Tugtupite gets its unique name from the location of its discovery in southwest Greenland. This semi-transparent to opaque mineral species is usually pink to red and often mottled with white, gray or black. Nicknamed the "Reindeer Stone," tugtupite is tenebrescent; when stored in darkness, the gem's color will fade, but returns immediately upon exposure to daylight. Among collectors, tugtupite is also prized for its luminescent properties: strong fluorescence and less commonly, phosphorescence, when the gem continues to fluoresce even after the ultraviolet light source has been removed.
December's birthstone, turquoise was among the first gemstones ever mined. Stunning sky blues to stimulating sea greens have made turquoise one of the most popular color trends in jewelry history. Copper gives turquoise its range of blue hues while iron is responsible for its green colors. Treasured since the days of ancient Egypt, and the thousands of years since, turquoise is said to bring good fortune and happiness to those who wear it.
Also called the "TV rock" or "television stone," ulexite is known for its unusual optical characteristics, notably its ability to transmit images through its natural fibers. A piece of writing placed underneath the stone appears on the surface of the stone! Ulexite was named for German chemist G. L. Ulex, who first correctly analyzed the species in 1850. Most specimens are milky and very poor quality, but those stones that are cut as cabochons often display a strong cat's eye effect.
Umbalite is also known as Malaya (Malaia) garnet. Umbalite is a relatively new member of the garnet group. First noticed in the 1960s, it was mixed in with parcels of rhodolite garnets from the Umba River Valley in East Africa. Many buyers rejected the material, so local miners and dealers gave it the Swahili name of “Malaya”, which translates to “out of the family”. Testing eventually confirmed that this new gem was a mixture of pyrope and spessartite garnet. Its lively color ranges from light to dark pink, red, and yellowish orange. After overcoming initial objections, it carved a small, but dedicated niche in the market in the 1980s, particularly in the United States. Today, umbalite is one of the more expensive garnets, and its only known sources are Kenya and Tanzania.
Unakite is a type of granitic rock that features mottled patterns of green epidote, white to gray quartz, and pink feldspar, occasionally with black veining. This compact, hard gem is most often seen as cabochon gems, carvings and beads or sold as tumbled rough.
Named after Niels Viggo Ussing, professor of Mineralogy at the University of Copenhagen, this rare silicate mineral can be found in only a few locations worldwide including Greenland and northern Russia. It typically has a massive habit and can be light pink, lilac-blue, and in rare cases dark violet-red.
Uvarovite is a highly desirable, yet widely unknown garnet species. Discovered in the 1830's in Russia, it was named in honor of Count Sergey S. Uvarov, a 19th century Russian statesman, scholar and avid mineral collector. Especially prized by collectors, uvarovite is hard to find anywhere, especially in sizes greater than 0.25 carats. Uvarovite ranges in color from medium to dark green and is best known for its granular, drusy masses which reveal well-formed dodecahedral or trapezohedral crystals under magnification.