Turquoise in the context of Opacity (optics)

An alpine lake is a high-altitude lake in a mountainous area, usually near or above the tree line, with extended periods of ice cover. These lakes are commonly glacial lakes formed from glacial activity (either current or in the past) but can also be formed from geological processes such as volcanic activity (volcanogenic lakes) or landslides (barrier lakes). Many alpine lakes that are fed from glacial meltwater have the characteristic bright turquoise green color as a result of glacial flour, suspended minerals derived from a glacier scouring the bedrock. When active glaciers are not supplying water to the lake, such as a majority of Rocky Mountains alpine lakes in the United States, the lakes may still be bright blue due to the lack of algal growth resulting from cold temperatures, lack of nutrient run-off from surrounding land, and lack of sediment input. The coloration and mountain locations of alpine lakes attract lots of recreational activity.

Alpine lakes are some of the most abundant types of lakes on Earth. In the Swiss Alps alone, there are nearly 1,000 alpine lakes, most of which formed after the Little Ice Age. As global temperatures continue to rise, more alpine lakes will be formed as glaciers recede and provide more run-off to surrounding areas, and existing lakes will see more biogeochemical changes and ecosystem shifts. An alpine lake's trophic state (i.e., level of biological productivity) progresses with age (e.g., low productivity after formation and increased productivity with vegetation and soil maturity in the surrounding watershed), but anthropogenic effects such as agriculture and climate change are rapidly affecting productivity levels in some lakes. These lakes are sensitive ecosystems and are particularly vulnerable to climate change due to the highly pronounced changes to ice and snow cover. Due to the importance of alpine lakes as sources of freshwater for agricultural and human use, the physical, chemical, and biological responses to climate change are being extensively studied.

The Dawenkou culture was a Chinese Neolithic culture primarily located in the eastern province of Shandong, but also appearing in Anhui, Henan and Jiangsu. The culture existed from 4300 to 2600 BC, and co-existed with the Yangshao culture. Turquoise, jade and ivory artefacts are commonly found at Dawenkou sites. The earliest examples of alligator drums appear at Dawenkou sites. Neolithic signs, perhaps related to subsequent scripts, such as those of the Shang dynasty, have been found on Dawenkou pottery. Additionally, the Dawenkou practiced dental ablation and cranial deformation, practices that disappeared in China by the Chinese Bronze Age.

The Steppe Route was an ancient overland route through the Eurasian Steppe that was an active precursor of the Silk Road. Silk and horses were traded as key commodities; secondary trade included furs, weapons, musical instruments, precious stones (turquoise, lapis lazuli, agate, nephrite) and jewels. This route extended for approximately 10,000 km (6,200 mi). Trans-Eurasian trade through the Steppe Route preceded the conventional date for the origins of the Silk Road by at least two millennia.

Turquoise is a cyan color, based on the mineral of the same name. The word turquoise dates to the 17th century and is derived from the French turquois, meaning 'Turkish', because the mineral was first brought to Europe through Turkey from mines in the historical Khorasan province of Iran (Persia) and Afghanistan today. The first recorded use of turquoise as a color name in English was in 1573.

The X11 color named turquoise is displayed on the right.

The Boring Billion, otherwise known as the Mid Proterozoic and Earth's Middle Ages, is an informal geological time period between 1.8 and 0.8 billion years ago (Ga) during the middle Proterozoic eon spanning from the Statherian to the Tonian periods, characterized by more or less tectonic stability, climatic stasis and slow biological evolution. Although it is bordered by two different oxygenation events (the Great Oxygenation Event and Neoproterozoic Oxygenation Event) and two global glacial events (the Huronian and Cryogenian glaciations), the Boring Billion period itself actually had very low oxygen levels and no geological evidence of glaciations.

The oceans during the Boring Billion may have been oxygen-poor, nutrient-poor and sulfidic (euxinia), populated by mainly anoxygenic purple bacteria, a type of bacteriochlorophyll-based photosynthetic bacteria which uses hydrogen sulfide (H₂S) for carbon fixation instead of water and produces sulfur as a byproduct instead of oxygen. This is known as a Canfield ocean, and such composition may have caused the oceans to be colored black-and-milky-turquoise instead of blue or green as later. (By contrast, during the much earlier Purple Earth phase during the Archean, photosynthesis was performed mostly by archaeal colonies using retinal-based proton pumps that absorb green light, and the oceans would be magenta-purple.)

The Knesset Eliyahoo Synagogue (Hebrew: בית הכנסת אליהו, lit. 'Gathering of Elijah'), also Knesset Eliyahu and the Blue Synagogue, is an Orthodox Jewish congregation and synagogue, located at 55, Dr. V.B. Gandhi Marg, in the Kala Ghoda neighborhood, Fort, in downtown Mumbai, in the state of Maharashtra, India. Completed in 1884, it is the second oldest Sephardic synagogue in Mumbai. The Taj Mahal Palace Hotel, and Oberoi Trident are nearby.

The synagogue was established by Jacob Elias Sassoon and the building is maintained by the Jacob Sassoon Trust. The building's significance is attributed to its Jewish traditions as well as Indian and English colonial influences. It was designed by the British architectural firm Gostling & Morris of Bombay. The basement part of the edifice is built in stone masonry and the superstructure is built in brick masonry. The exterior facade of the synagogue was painted turquoise, was returned to its original colour of white, with bright indigo boarders during a restoration process in 2018–2019. The sanctuary within the interior of the building is in western direction, towards Jerusalem.

Cloisonné (French: [klwazɔne]) is an ancient technique for decorating metalwork objects with colored material held in place or separated by metal strips or wire, normally of gold. In recent centuries, vitreous enamel has been used, but inlays of cut gemstones, glass and other materials were also used during older periods. Cloisonné enamel was probably developed as an easier imitation of cloisonné work using gems. The resulting objects can also be called cloisonné.

The decoration is formed by first adding compartments (cloisons in French) to the metal object by soldering or affixing silver or gold as wires or thin strips placed on their edges. These remain visible in the finished piece, separating the different compartments of the enamel or inlays, which are often of several colors. Cloisonné enamel objects are worked on with enamel powder made into a paste. The objects are fired in a kiln for finishing. If gemstones or colored glass are used, the pieces need to be cut or ground into the shape of each cloison.

Serabit el-Khadim (Arabic: سرابيط الخادم Arabic pronunciation: [saraːˈbiːtˤ alˈxaːdɪm]; also transliterated Serabit al-Khadim, Serabit el-Khadem) is a locality in the southwest Sinai Peninsula, Egypt, where valuable resources such as turquoise were mined extensively in antiquity, mainly by the ancient Egyptians. Archaeological excavation, initially by Sir Flinders Petrie, revealed ancient mining camps and a long-lived Temple of Hathor, the Egyptian goddess of sensual power, who was favored as a protector in desert regions and known locally as the mistress of turquoise.  

The Sinai Peninsula between Egypt and Western Asia was an important mining area for copper and malachite in ancient Egypt, Serabit el-Khadim being the most important copper mining site in the region. The temple was first established during the Middle Kingdom in the reign of Senusret I (reigned 1971 BC to 1926 BC) and was partly reconstructed in the New Kingdom. The temple is located about 10 kilometers north of Wadi Maghara, another archaeological site, and roughly 43 kilometers east of the modern-day city, Abu Zenima. The function of the temple was to honor the goddess Hathor who acted as a guide to the Egyptian Kings who had undertaken expeditions to utilize these mines, and to glorify the power of the Pharaohs that had overseen these missions.

Azure spar, sometimes azur-spar, is a trivial and commercial, partly obsolete name for several of the most famous bright blue or blue-colored minerals, which also have similar names, most notably for lazurite and azurite, and also for the less commonly used lazulite.

In addition, Robert Jameson in his fundamental works of 1804-1821 also included hauyne as a separate mineral species and the so-called “calaite”, which in the 1820s meant only turquoise, among the azure feldspars.

Amenemhat IV (also known as Amenemhet IV) was the seventh and penultimate king of the late Twelfth Dynasty of Egypt during the late Middle Kingdom period. He arguably ruled around 1786–1777 BC for about nine regnal years.

Amenemhat IV may have been the son, grandson, son-in-law, or stepson of his predecessor, the powerful Amenemhat III. His reign started with a seemingly peaceful two-year coregency with Amenemhat III. He undertook expeditions in the Sinai for turquoise, in Upper Egypt for amethyst, and to the Land of Punt. He also maintained trade relations with Byblos as well as continuing the Egyptian presence in Nubia.

The sekhem scepter is a type of ritual scepter in ancient Egypt. As a symbol of authority, it is often incorporated in names and words associated with power and control. The sekhem scepter (symbolizing "the powerful") is related to the kherp (ḫrp) scepter (symbolizing "the controller") and the aba scepter (symbolizing "the commander"), which are all represented with the same hieroglyphic symbol. These scepters resembled a flat paddle on a papyrus umbel handle. Its symbolic role may have originated in Abydos as a fetish of Osiris. The shape of the scepter might have derived from professional tools.

Cho Oyu (Nepali: चोयु; Tibetan: ཇོ་བོ་དབུ་ཡ; Chinese: 卓奥友峰) is the sixth-highest mountain in the world at 8,188 metres (26,864 ft) above sea level. Cho Oyu means "Turquoise Goddess" in Tibetan. The mountain is the westernmost major peak of the Khumbu sub-section of the Mahalangur Himalaya 20 km west of Mount Everest. The mountain stands on the China–Nepal border, between the Tibet Autonomous Region and Koshi Province.

Just a few kilometres west of Cho Oyu is Nangpa La (5,716m/18,753 ft), a glaciated pass that serves as the main trading route between the Tibetans and the Khumbu's Sherpas. This pass separates the Khumbu and Rolwaling Himalayas. Due to its proximity to this pass and the generally moderate slopes of the standard northwest ridge route, Cho Oyu is considered the easiest 8,000 metre peak to climb. It is a popular objective for professionally guided parties.