Turquoise is one of those minerals recognized by “almost everyone.” It is a hydrated copper aluminum phosphate that is most often found in phosphorus-rich alteration zones of porphyry copper deposits that have been subjected to infusions of hydrothermal solutions. There are also minor turquoise occurrences: 1) in volcanic rocks such as Cripple Creek, Colorado where the mineral formed in cracks and faults associated with the gold-producing volcanic caldera; and 2) as nodules in phosphatic rich rocks subjected to meteoric (rainwater) water infiltration such as the Sanders Project in North Carolina.
R.J. King, in a great 2002 article in Geology Today, explained, in a very understanding manner, the complex formation of the porphyry copper model: as a supergene mineral turquoise forms when meteoric water percolates down through the copper porphyry minerals and rocks. Dissolved oxygen in the water oxidizes the copper sulfides to soluble sulfates, and the acidic copper-laden solution then reacts with aluminum and potassium minerals in the host rocks and turquoise is precipitated at a relatively low temperature (~200-400 F).
I rarely collect or purchase turquoise since :1) the “good stuff” from reputable dealers seems quite expensive; 2) I have not taken the time to examine closely the material from different localities; 3) the market is full of: A} dyed minerals forming imitations of turquoise; B} various synthetics (plastic) produced to closely resemble gem quality material: and C} who knows how the gems have been treated, hardened, or stabilized with polymers or resins. The latter is a legitimate process since it hardens a soft and often porous stone producing a more durable gem and often enhances the color. Reputable dealers will inform buyers about any stone treatments. What is often untold to buyers examining less expensive jewelry is that the tiny pieces or chalky turquoise (unsaleable as is) is first ground to a power and then mixed with resins and usually a color enhancer and poured into block molds. Craftsmen then cut the block in smaller pieces, form a shape, polish, and stick the creation into a ring or pendant. Perfectly legit I guess but dealers just need to inform buyers. I have purchased pendants for youngsters cut from a block, attached to backing, polished and set---and they were beautiful.
Two minerals that are quite involved in the fake turquoise market are howlite and magnesite. The former is a hydrated calcium borosilicate that is porous and veined with impurities. The subvitreous luster and the texture of the mineral allows for easy dying with various shades of blue materials, that along with the veining, certainly “resembles” turquoise. However, diluted hydrochloric acid will turn howlite a green color.
At most rock and mineral shows several jewelry vendors will display rings and pendants with stones labeled White Buffalo Turquoise, generally white in color (to honor the sacred white buffalo animal; marketing at its best). That name is a real misnomer since the stone is composed of calcite, dolomite and dark iron oxide---no copper, aluminum or phosphate, but depending on your source perhaps quartz, zeolites or magnesite. Sellers go to great length to disguise this fact but pressed will say it is “not actually turquoise but of the same family or is found with turquoise or is the favored stone of Native Americans.
White buffalo turquoise is a trade name and officially “true” white buffalo comes only from a single mine near Tonopah, Nevada. However, the majority of white buffalo being marketed is actually howlite, and has been described by some dealers as rare, even rarest of its kind, limited in extremely quantity (so buy right away), unique, avoid moisture, sunlight, heat or humidity (but scientific properties make it resistant to damage), popular as Native Americans use it to honor their heritage, a powerful healing stone, brings clarity to decision making, one of the oldest known gemstones in North America and you name it etc. There is a long history associated with the marketing of white buffalo, and this information, although interesting, is far beyond the scope of this small article.
So, then there is “magnesite turquoise” often marketed as turquoise (dishonest) or magnesite turquoise (at least partially honest). The mineral magnesite is a soft, white or pastel magnesium carbonate that like howlite may be dyed and passed off as turquoise. Unlike howlite-type turquoise, turquoise magnesite, as a carbonate, will effervesce in dilute hydrochloric acid. Karl Sawyer in 2026 Lil Gem noted: “magnesite turquoise is a captivating gemstone that has intrigued jewelry enthusiasts and collectors alike with its striking appearance and unique origins. Often admired for its vibrant blue-green hues and intricate veining, this stone offers a beautiful alternative to natural turquoise, blending aesthetic appeal with fascinating geological characteristics.” On the other hand, Crystal Alamac dot com stated: turquoise is the most-faked gemstone in the world. An estimated 90% of ‘turquoise’ sold cheaply is actually dyed howlite, dyed magnesite, reconstituted turquoise dust, or plastic. Buyers beware; “you get what you pay for,” and trust your reputable dealer.
Everything about the physical properties of turquoise seem variable. The hardness (Mohs) is usually listed as 5.0-6.0 although the material at Cripple Creek, Colorado, has a hardness of 7.0 (Mohs). The color is listed by MinDat as bright blue, sky-blue, pale green, blue-green, turquoise-blue, apple-green, green-gray. The luster can range from quite “shiny” subvitreous to earthy and dull. It occurs as veinlets or nodules or crusts or massive or cement filling in breccia.
Turquoise is CuAl6(PO4)4(OH)8 · 4H2O and forms a solid solution with chalcosiderite where the aluminum is replaced by ferric iron (Fe3+). There is also a solid solution series between planerite where the CuAl6 in turquoise is replaced by aluminum phosphate Al6(PO4)2. Turquoise is much more than a pretty blue mineral—it is variable and complex.
Specimens of turquoise purchased at a rock show 30 years ago. Both ID and locality could be suspect!
As stated, I rarely hunt for, or collect, turquoise although I have a few specimens. However, at the 2026 Tucson Show a turquoise specimen from Shannons Family Minerals really caught my eye. Something my limited knowledge of minerals had not realized existed---turquoise crystals. Not the nodules or soft crusty material but honest turquoise crystals. Wow, always nice to get a pleasant surprise to increase your knowledge base.
The best recognizable turquoise crystals, at least in the U.S, are from the Bishop Copper Prospect near Lynch Station, Campbell County, Virginia. The Copper Prospect is in the old iron (late 1700s – 1880s) and manganese (~1868 – 1945) belt in the James River- Roanoke River Mining District. Crystalized turquoise evidently was reported from the area in 1910 in a Bureau of Mines publication (Sterrett). W.T. Schaller of the USGS acquired a specimen (from J.H. Watkins) of the turquoise and reported on its physical, chemical and optical properties (1912); however, the rareness and lack of outcrops evidently scared most prospectors away from the area and it was not until the early 1940s that local collectors sort of rediscovered the source of the turquoise. In the 1960s local collectors started working the old mine dumps rather than attempting to locate specimens in the deserted manganese mines and were somewhat successful. Bland (1963) wrote, “in order to obtain good material, one must did through a mixture of dirt, roots and logs… and at the three-foot lever, one runs into a layer of brown to black mica [and below this] a layer of schist and quartz fragment [and it becomes necessary to wash every piece to locate turquoise crystals].” For years the Bishop Copper Prospect seemed the only locality of crystalized turquoise. However, by Barwood’s 2003 publication 26 other localities were recognized. Unfortunately, I have been unable to locate a seminal paper with all localities listed and the number of localities may now exceed 27. I suppose one could sort through all MinDat turquoise localities and try to locate crystalized specimens. For example, I found the Bachman Mine in Pennsylvania listed turquoise as present and David Fryauff has posted a photograph of the crystals. For me, another project for another day. This information about the Bishop Copper Prospect was retrieved from a Mineralogical Record article by Henry Barwood (2003).
Hundreds, probably thousands, of articles and a large
number of books describing turquoise have been penned by a variety of worldwide
authors, including the description of King Tyre in the Christian Bible: "You
were in Eden, the garden of God; Every precious stone was your covering: The
ruby, the topaz and the diamond; The beryl, the onyx and the jasper; The lapis
lazuli, the turquoise and the emerald; And the gold (NASB version,
Ezekiel 28:13). The gem has a long known history as it was mined in the Siani
of Egypt since at least the First Dynasty and possibly before—at least 3000
BCE. The Chinese have mined turquoise since at least the Shang Dynasty ca. 1600–1046
BCE. In the U.S. Native Americans mined the gem in the Cerrillos Hills of New
Mexico over a thousand years ago. So, readers, explore the internet and
libraries and your reading about turquoise will last a lifetime.
REFERENCES CITED
Barwood, H., 2003, Famous mineral localities: The Bishop copper prospect near Lynch Station, Campbell County, Virginia: Mineralogical Record, vol. 34, no. 3.
Bland, R. J. Jr., 1963, Operation turquoise crystals: Rocks and Minerals, vol. 38, nos.11-12, November-December).
King, R.J., 2002, Turquoise: Geology Today, vol.18, no. 3.
Schaller, W.T., 1912, Crystallized turquoise from Virginia: American Journal of Science, vol. 33.
Sterrett, D.B., 1910, Gems and precious stones: Bureau of Mines, Mineral Resources of the United States, Part II--Nonmetals.