There is much confusion surrounding the subject of Turquoise and those minerals thatform under similar conditions. This post is an attempt to shed some light on the unique chemical makeup of Turquoise and its closely related siblings. Turquoise is formed by a complex combination of aluminum, copper, phosphorus, water, and other local ingredients that may change the color or add matrix (host rock).Turquoise is found at elevations between 3,000 - 8,500 feet and typically in dry, arid climates.Other, very similar minerals also form under these conditions- andfive of theseare classified under the Turquoise Mineral Group. The turquoise mineral group includes:Turquoise, Faustite, Chalcosiderite, Aheylite, and Planerite. For simplicity sake,most artists and galleries working with these stones classify all the members of the turquoise mineral group as "Turquoise". They are extremely similar stones, made different by the levels of zinc, iron, and copper present in the ground where they form. But they all fall under the umbrella of the Turquoise Mineral Group. Other than Turquoise, two of the most commonly seen members of the turquoise group include Chalcosiderite and Faustite. Chalcosiderite replaces iron in its chemical formula, instead of the aluminum in Turquoise. However some Chalcosiderite contains both iron and aluminum and can be difficult to chemically distinguish from Turquoise. Some famous mines that produce this form of Chalcosiderite include theNew Lander, Damele, andPeaco*ckmines. Peaco*ck Turquoise Necklace Faustite replaces zinc in its chemical formula, instead of the aluminum in Turquoise. However, once again, Faustite can contain both zinc and aluminum and becomes difficult to distinguish from turquoise. Famous mines that produce this form of Faustite include the Carico LakeandOrvil Jackmines. While both Turquoise and Variscite form under similar conditions, we identify them as separate stones on our site. Turquoise is a hydrous phosphate of aluminum and copper and Variscite is considered a hydrated aluminum phosphate. Here's their chemical makeup: Variscite:AlPO4•2H2O Turquoise:CuAl6(PO4)4(OH8)•4H2O For those of us without degrees in Geology, those equations look like Greek. To put it in layman terms, Variscite is a brighter green and typically has less complex matrix than its sister Turquoise. Varisciteis usually seen to be on its own- it’s a brighter green color- and we try to identify it as its own mineral. This can get complicated too however, because once again, certain veins can produce both Variscite and Turquoise (or a blend) in the same deposit.One mine that can produce both Variscite and Turquoise is the Broken Arrowmine in Nevada.The Turquoise Mineral Group:
Chalcosiderite:
Faustite:
Variscite:
3 comments
Andrea
I really enjoyed this explanation. Thank you for making it available!
RV Karanth
Nicely written article with mineralogy background.
Michael Scharf
Thanks. This is just the kind of information I crave. I collect and love SW jewelry and fetish carvings and I love your site. One of my favorite pendants I got from you. It is a two-sided maiden pendant by Rita Begay.
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More from: Jewelry Materials Turquoise Mines
The article you mentioned dives into the intricate world of turquoise and its mineral group, outlining their chemical compositions, formations, and distinctions. I'm quite familiar with this topic, backed by geological knowledge and a passion for gemology. Let's break down the concepts discussed:
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Turquoise Mineral Group: Comprising minerals formed from aluminum, copper, phosphorus, and local elements under specific conditions (elevations of 3,000 - 8,500 feet in arid climates). This group includes Turquoise, Faustite, Chalcosiderite, Aheylite, and Planerite. Despite variations in zinc, iron, and copper levels, they're collectively categorized under the Turquoise Mineral Group.
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Chalcosiderite: A mineral that replaces iron in its chemical formula (in place of aluminum in Turquoise). Some Chalcosiderite may contain both iron and aluminum, making it challenging to distinguish from Turquoise. Mines like New Lander, Damele, and Peaco*ck are known for producing this variant.
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Faustite: Replacing zinc in its chemical formula (instead of aluminum in Turquoise), Faustite might also contain both zinc and aluminum, posing identification challenges. Mines like Carico Lake and Orvil Jack are known for Faustite production.
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Variscite: Though forming under similar conditions to Turquoise, Variscite is a separate stone, chemically a hydrated aluminum phosphate (AlPO4•2H2O). It's distinguished by its brighter green color and simpler matrix compared to Turquoise. However, complications arise as some deposits may yield both Variscite and Turquoise, such as the Broken Arrow mine in Nevada.
Understanding the chemical makeup of these minerals is key to distinguishing between them. For instance, Variscite's formula (AlPO4•2H2O) showcases its hydrated aluminum phosphate structure, setting it apart from Turquoise (CuAl6(PO4)4(OH8)•4H2O), which is a hydrous phosphate of aluminum and copper.
The article provides valuable insights into these distinctions and complexities. The comments from readers, expressing gratitude for the detailed explanation, affirm the article's informative nature. The writer's ability to cater to both enthusiasts and those new to geology by simplifying complex chemical equations into layman's terms demonstrates a strong grasp of the subject matter.
