“Dendrite turquoise is exceedingly rare. The fern-like pattern in the matrix is produced by the crystallization of a foreign mineral, usually an oxide of manganese, at the time the turquoise itself is being formed.” Turquoise Unearthed, Joe Dan Lowry.
"A dendrite is a superficial deposit of manganese oxide that has crystallized in a multi-branching tree-like pattern. This pattern is what fools us into thinking they are plant fossils. Dendrites form as water rich in manganese and iron flows along tiny cracks between layers of limestone and other rock types. Dendrites may also consist of iron oxides and other minerals, and can also form in quartz materials like agate and jasper." The Fossil Cartel.
Dendrite formation in turquoise is very rare. It has often been associated with mines where there is fossil turquoise formation, like Lone Mountain, although the fern like dendrites are not formed within organic fossil hosts but rather from the interaction of the mineral oxidation within the turquoise formation.
This large (almost 60 carats) cabochon of Red Mountain shows an extraordinary pattern of dendritic turquoise formation, rare in any case but especially in such a large cabochon. It is difficult to set a price for this turquoise since there are few comparable stones with which to compare.
In comparison fossil turquoise is a misnomer because the turquoise is not itself a fossil but rather uses organic fossilized remains as a host in which to form the secondary mineral just as turquoise forms in cracks of host rock or in clay pockets both of which protect the formation of the turquoise over immense periods of time.
Pictured is a fossil egg with turquoise formation. This was sold to me as a dinosaur egg. Dinosaurs lived between 245 million and 66 million years ago while the oldest turquoise formation dates to perhaps 30 million years ago. Still, this is certainly an egg perhaps from a reptile or a bird, the descendants of the dinosaurs, or maybe, a dinosaur.
Another well-known example of fossil turquoise are clams. Pictured is a clam fossil from Carico Lake which has produced many examples. We say clams but this is shorthand for any bi valve marine organisms with two hinged shells.
Finally, we see a photo of a magnificent Charles Loloma nugget necklace, photographed by Arland Ben, made from Lone Mountain fossil turquoise formed within the fossilized remains of marine tubular plant organisms. Charles made seven of these necklaces. Fossil turquoise of this grade from Lone Mountain is among the most rare of all turquoise.
Mike Ryan II
Santa Fe
October 2023
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