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GIA's Guide to Gemstones: Gem Encyclopedia. GIA's Gem Encyclopedia is a virtual journey through the science and lore of gemstones from across the globe. Each precious stone page features additional detailed gemological information, a buyer's guide, photos, videos & research. Filter By Country. View Gems as.
What is Turquoise? Turquoise is an opaque mineral that occurs in beautiful shades of blue, bluish green, green, and yellowish green. It has been treasured as a gemstone for thousands of years. Isolated from one another, the ancient people of Africa, Asia, South America and North America independently made turquoise one of their preferred …
Ruby, Sapphire, and Fancy Sapphire. Most people don't realize that ruby and sapphire are both gems of the mineral corundum. Both of these gemstones have the same chemical composition and the same mineral structure. Trace amounts of impurities determine if a gem corundum will be a brilliant red ruby or a beautiful blue sapphire.
Diamonds: Learn about the properties of diamond, its many uses, and diamond discoveries. Moonstone is a very popular gemstone. The source of its popularity is a glow of white, silver or blue light that floats under the surface of the gem. A rare variety displays a tiny rainbow within the gem.
Primary Gemstone Deposits. The gemstones are found in their original host-rock. The profitability of such a deposit is highly dependent from the concentration of gemstones (per ton of rock) and the weathering stage of the host-rock. A lot of large-scale diamond mining operations work primary kimberlite deposits in the search for diamonds.
Rutilated quartz is a type of quartz crystal that contains needle-like inclusions of the mineral rutile (titanium dioxide). These fine, golden, or reddish-brown needle-like threads of rutile can be distributed throughout the quartz crystal in various patterns, creating striking and mesmerizing visual effects. The rutile inclusions are often …
Stromatolites are layered structures formed by the growth of cyanobacteria (formerly called blue-green algae) in shallow water environments. Some stromatolite specimens may exhibit interesting patterns and colors due to variations in mineral composition, sedimentation rates, and environmental conditions during their formation. …
Arfvedsonite is a relatively rare mineral that belongs to the amphibole group, a subgroup of silicate minerals. It is a complex inosilicate mineral with the chemical formula (Na, K)3(Fe, Mn)4Fe2Si8O22(OH)2. This formula indicates that arfvedsonite is primarily composed of sodium (Na), potassium (K), iron (Fe), manganese (Mn), silicon (Si), and oxygen (O), …
Gemology Project. Next to the refractometer and the loupe, the microscope is probably the most-used instrument among gemologists. Its obvious use is for magnification of internal …
Earth Science. Key Terms. geology, rock, mineral, pegmatite, crystal, gem. Key Concepts. Processes of mineralization and crystallization. Differences between gems and minerals. …
Hobart M. King is the manager and publisher of Geology. He is a geologist with over 45 years of experience, has a Ph.D. in geology, and is a GIA graduate gemologist. Much of his work has focused on coal geology, industrial minerals, gemology, geologic hazards, and geoscience education. He has authored many of the internet's most popular ...
Heliodor. Modified date: 11/07/2023. Heliodor is a gemstone that belongs to the beryl family, which also includes well-known gemstones such as emerald and aquamarine. It is a relatively rare and lesser-known gemstone compared to its counterparts, but it possesses its own unique beauty and charm. Heliodor derives its name from the Greek words ...
The Pink Star Diamond is a truly remarkable and exceedingly rare gemstone that has captured the attention of collectors, investors, and enthusiasts around the world. Renowned for its exceptional color and size, this diamond stands as a testament to the Earth's geological forces and the incredible beauty that can result from millions of years …
Turquoise. Turquoise A blue to bluish- green gem material that has been used for over 6000 years. Strawberry Quartz. Strawberry Quartz is a red to pink quartz with inclusions that look like strawberry seeds. Ammolite. Ammolite is a fossil and a gemstone. It is shell material from fossil ammonites. Aquamarine.
Here are some of the key physical properties of banded agate: Hardness: Banded agate has a hardness of around 6.5 to 7 on the Mohs scale, making it relatively durable and resistant to scratching. This hardness allows it to withstand normal wear and tear, making it suitable for use in jewelry and decorative objects.
In conclusion, peridot is a magnesium iron silicate gemstone with a vitreous lustre. It has a hardness of 6.5-7 and ranges in color from yellow to green. Peridot crystallizes in the orthorhombic crystal system and has poor cleavage. Its specific gravity ranges from 3.2 to 4.3, and it is translucent to transparent.
A geology dictionary of geological terms from Geology. ... A fault that has both horizontal and vertical elements of displacement. Obsidian. ... gemstone or other valuable mineral substance, which is rich enough in concentration that it can be mined and processed at a profit.
Blue zircon is a naturally occurring gemstone belonging to the zircon family. It is characterized by its vibrant blue colors, which range from pale blue to deep azure, and is widely recognized for its intense sparkle and high refractive index. Zircon is a mineral composed of zirconium silicate and can be found in a variety of colors, with blue ...
Opal Formation: Fire opals, in particular, owe their unique colors to the presence of tiny traces of iron oxide or other impurities in the silica solution. These impurities contribute to the opal's warm, fiery colors, which range from red to orange to yellow. As the silica precipitates, it forms a network of microscopic spheres, diffracting ...
Strontium titanate was a very popular diamond simulant in the 1950s through the 1970s and was sold under a variety of trade names. Although its surprising fire captured the attention of consumers, its lack of durability resulted in consumer disappointment. It was replaced by materials such as YAG and cubic zirconia that are superior in hardness ...
Olivine is the name of a group of rock-forming minerals that are typically found in mafic and ultramafic igneous rocks such as basalt, gabbro, dunite, diabase, and peridotite. They are usually green in color and have compositions that typically range between Mg 2 SiO 4 and Fe 2 SiO 4. Many people are familiar with olivine because it is the ...
Geology Tools Rock hammers, field bags, hand lenses, maps, hardness picks, gold pans. Diamond is much more than the world's most popular gemstone and hardest natural material. Today man-made diamonds are being used in computers, speakers, cutting tools, bearings, laser windows, wear-resistant parts and much more.
The most popular bicolor tourmaline is "watermelon tourmaline." It has a pink interior and a green rind - just like a slice of watermelon. The closer the colors match those of a real watermelon, the more people enjoy them and the higher the price. Tourmaline crystals are also faceted to produce bicolor gems.
How gemstones are formed. Gemstones are formed through a variety of geological processes over millions of years. Here are some of the most common ways that gemstones are formed: Igneous rock formation: …
Arizona is world-famous for its turquoise, peridot, and petrified wood. The state is also famous for copper, and a variety of copper minerals are mined as gemstones. These include azurite, chrysocolla, and malachite . Other Arizona gem materials include agate, amethyst, garnet, jade, jasper, obsidian, onyx, and opal.
Celestine. Celestine, also known as celestite, is a mineral that belongs to the sulfate mineral group. It is named after the Latin word "caelestis," which means "heavenly" or "celestial," due to its beautiful sky …
Agate is a popular and highly marketable stone amongst gem enthusiasts worldwide. This is mostly due to its colorful displays, mystifying geological origins, and its spiritual and cultural affiliations. Updated September 10, 2022. How to Pronounce Agate. Despite the simple spelling of this gemstone, many inquire about its proper pronunciation.
Jade. "Jade" is a cultural term used for a translucent gem material consisting of either jadeite or nephrite. The typical color cut into gemstones and used in ornamental work is a bright to deep green. However, jade can be white, pink, purple, gray, black, or other colors. Jade is a durable stone, well suited for use in jewelry.
Morganite is a captivating and beautiful gemstone that belongs to the beryl mineral family. It is prized for its delicate and alluring pink to peachy-pink hues, which evoke a sense of elegance and romance. Named after the American financier and gem enthusiast J.P. Morgan, Morganite has gained popularity and recognition among gemstone …
Beryl. Beryl is a mineral composed of beryllium aluminium cyclosilicate, with the chemical formula Be3Al2 (Si6O18). It belongs to the cyclosilicate mineral group, which is characterized by its unique arrangement of silicate tetrahedrons forming rings. Beryl is widely known for its stunning range of colors and its use as a gemstone in …
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