Taafféite:
Etymology : from ECR TAAFFE. Discovered by ANDERSON & CLARINGBULL in 1951 à LNS, Sri-lanka.
Tanzanite: Ca2Al3(Si2O7)(SiO4)(O OH) 
Etymology: Portuguese prospector Manuel d’Souza discovered this gem in Tanzania in 1967 while searching for sapphire. Tanzanite was named after its country of origin by Henry Platt, vice president of Tiffany & Co. in New York, one of the world’s most famous jewelers who began a marketing campaign to introduce tanzanite to the public in the 1980s. The promotion of that gemstone was helped by Liz Taylor regarding the color of her eyes... the same than Tanzanite.
Tanzanite in its rough state is usually a reddish brown color. It requires artificial heat treatment to 600 °C in a gemological oven to bring out the blue violet of the stone. Tanzanite is a rare gem. It is found mostly in the foothills of Mount Kilimanjaro.
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Taouz 002
Etymology: Name of a locality in Morocco where a meteorite was found.
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Tatahouine
__ Etymology: Name of a locality in Tunisia where a meteorite was found.
The Tatahouine meteorite fell on June 27, 1931 at 1:30 am in Foum Tatahouine, Tunisia. A fireball was seen to explode in the Tunisian desert and many hundreds of small fragments showered down on the desert four kilometers Northeast from the village. The achondritic stones were thought to be apparently dispersed over a small strewn field (less than 1 square kilometer) on a hillside composed of Jurassic limestone and having a sandy desert soil. Over 12 kilograms was immediately collected by local Bedouins, principally as minute fragments, though they ranged in weight from 1 g or less to 2 kilograms. These were sent to the Muséum National d’Histoire Naturelle in Paris. In 1994, the French meteoriticist Dr. Alain Carion and his colleague and son Louis recovered many more specimens at the strewn field raising the total weight recovered apparently to approximately 13.5 kg
Tectite:
Etymology: Frome the Greeck « tektos » = molten.
glassy bodies of various shapes, found in isolated locations around the world and thought to have originated as meteorites or from meteorite impacts
Some of these stones have been cut in faceted gemstones as here with “Libyan glass”.
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Tissemoumine:
Etymology: Name of a locality in Morocco where a meteorite was found.
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Titanite: (or Sphene) CaTi(SiO5) 
Etymology: from German Titanit, so named because it contained titanium.
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Topaze
Etymology : from the name of the island in the Red Sea.
The topaz exisits in different varities as:
Topaz with Rutile 
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White Topaz: 
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Blue Topaz: 
The blue Topaz in natural color without enhancement is very rare.
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"Imperial Topaz": 
The imperial Topaz is coming only from two localities : Chundao Hill in Pakistan and Ouro Preto - Minas Gerais in Brasil.
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“Sky blue” Topaz: 
Its Aquamarine color is coming after treatment by radiation. Exposure to Gamma rays and a final heat treatment to burn off undesired brown and green overtones that appear during the process is most commonly used to produce the Sky Blue color (light pure blue color.) Sky Blue Topaz treatment with Gamma rays or Electrons does not have a high radiation level and can be released immediately.
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"Swiss blue" Topaz: 
Its Neon blue color is coming after treatment by radiation.
Exposure to neutrons in a linear reactor and or electrons in an electron accelerator combined with heat will produce the darker shades we know as London Blue and Swiss Blue.
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"London Blue" Topaz:
Exposure to neutrons in a linear reactor and or electrons in an electron accelerator combined with heat will produce the darker shades we know as London Blue and Swiss Blue.
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Tourmaline: Toermalijn, Tormalina, Turmaliini, Turmalin, Turmalín, Turmalina, Turmalină, Turmalinas, Turmaliner, Turmalīns, Turmalínu,
トルマリン, Турмалины, טורמלין, 碧玺, ทัวร์มาลีน.
Etymology : The name comes from the Sinhalese word "Thuramali" (තුරමලි) or "Thoramalli" (තෝරමල්ලි), which applied to different gemstones found in Sri Lanka.
Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gem comes in a wide variety of colors.
They are different species and varieties of Tourmaline,
Achroïte : white
Rubellite : red
Indigolite : blue
Elbaite : pink, yellow, brown
Dravite : yellow to brown
Verdeite : green
Schorl : Bluish or brownish black to Black. The most common species of tourmaline is schorl. It may account for 95% or more of all tourmaline in nature. The early history of the mineral schorl shows that the name "schorl" was in use prior to 1400 because a village known today as Zschorlau (in Saxony, Germany) was then named "Schorl" (or minor variants of this name).
Tourmaline Rubellite:
Etymology : from Ruby, regarding its red color.
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Triphylite: 
Etymology: from the Greek tri (three) and phyllon (leaf). This mineral is gray, red-grey, brown, or black
Discovered by Fuschs in 1834 dans the locality of HUHNERKOBEL, RABENSTEIN, in Germany.
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Tsavorite:
See Garnet (Tsavorite Garnet)->
Tugtupite:
Etymology: from the locality of the discovery : TUGTUP AGTAKORFIA, ILIMAUSSAQ, GROENLAND.
discovered by SOERENSEN in 1962.
Turquoise: CuAl6(PO4)4(OH)8•4H2O
Turchese, Turkis, Türkiis, Türkis, Türkiz, Turkoois, Turkoosi, Turkos, Turkuaz, Turkus, Turquesa, Tyrkys, Ngọc lam, فيروز, فیروزه, 土耳其玉概说, トルコ石, Бирюза, טורקיז, फीरोजा़
Turquoise is etymologically the ‘Turkish’ stone. The word was borrowed from Old French turqueise, short for pierre turqueise ‘Turkish stone’. The stone was so called because it was first found in Turkestan. The present-day form of the word, which dates from the 16th century, is due to the influence of modern French turquoise. It was first used as a colour adjective in the late 16th century.
The Turquoise was dicovered in 1678 by Tavernier.
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