is a rare lead chromate mineral and very rare as a faceted
gem. It is one of only 25 chromate minerals, all
of which are rare.
It is very soft with a Moh's hardness of only 2.5-3.0 and has a very high dispersion, but this is masked
by the intense color. Crocoite's
intense reddish-orange color is almost unique in the
gem world and makes this very rare gem even more
desirable. Its density is extremely high
at 5.9-6.1 due to its lead (Pb) content of about
64% and chromium (Cr) content of about 16%. This high
density makes Crocoite among the densest of all translucent
minerals. Because of its density, Crocoite has an unusually
high index of refraction of 2.31-2.66, which approximates
that of Diamond (2.417).
Crocoite is associated with other secondary lead (Pb)
minerals such as Cerussite,
and a number of rare chromates.
German mineralogist Johann Gottlob Lehmann (1719-1767)
identified orange-red specimens from the type locality
at the Tsvetnoi Mine near Sverdlowsk, Russia, as a new
mineral in 1763. He called it "red-lead ore"
which became known as "red lead of Siberia"
and later "Siberian red lead." In 1770, German scientist
Peter Simon Pallas (1741-1811) ground specimens from
the same site into a bright yellow powder that he found
useful as a paint pigment and fabric dye which quickly
gained popularity throughout Russia and Europe.
red lead was known to contain lead but the remainder
of its chemical composition remained a mystery until
1797, when French chemist Louis Nicolas Vauquelin (1763-1829)
treated samples of Siberian red lead with acid to produce
an oxide that contained a previously undiscovered element;
a hard, lustrous, steel-gray metal with a high melting
point and a density similar to that of iron. Vauquelin
named this new element "chromium" after the
Greek word chrōma,
in allusion to the bright colors of its salts (compounds).
Vauquelin credited both R.J. Haüy and A.F. de Fourcroy
with the suggested name.
its discovery, Crocoite has been given many names and synonyms from many sources. The
following is a list of many of its names, along with
their sources and dates.
Nova minera Plumbi;
J.G. Lehmann, 1766
rouge; B.G. Sage, 1769
Minerai de plomb rouge;
P.S. Pallas, 1770
rhombeum fulvum; Rome de Itsle, 1772
Rotbleierz (or Rothes Bleierz);
A.G. Werner, 1774
Minera plumbi rubra;
J.G. Wallerius, 1775
Minera plumbi spathosa;
B.F.J. Hermann, 1789
Plombe rouge de Sibérie;
L. Macquart, 1789
R.J. Haüy, 1801
J.F.L. Hausmann, 1813
F.S. Beudant, 1832
Fr. Von Kobell, 1838
A. Breithaupt, 1841
C.U. Shepard, 1844
H.J. Brooke and W.H. Miller, 1852
1832 French mineralogist François-Sulpice Beaudant
(1787-1850) gave "red lead ore" its first formal
mineral name, "Crocoise," from the Greek word krokos,
a reference to the distinct color of its powder. This
name was later changed to "Crocoisite" and
eventually to the present name "Crocoite." Saffron
is a spice derived from the flower of the Crocus sativus
plant, commonly known as the saffron crocus. Saffron crocus bears up to four flowers, each with three vivid crimson stigmas, which are dried and
used as a seasoning and coloring agent in food.
best known source for exceptional specimens is the Adelaide
and other mines of the Dundas district, Tasmania, Australia.
Crocoite was found in Tasmania in about 1886, and ever
has been the most important source of Crocoite specimens and
gemmy crystals of this highly
sought-after mineral. According to the well-known Tasmanian amateur mineralogist
William Frederick Petterd (1849-1910) wrote: “The first
discovery of the mineral was made by Smith and Bell
at the Heazlewood silver-lead mine. It occurs there
in bright, shining hyacinth-red crystals, small as we
now know them from other portions of the island, arranged
in acicular bunches, penetrating and attached to a very
friable clayey gossan, intermixed with a little cerussite,
and more rarely pyromorphite.” By the time mineralogists
positively identified the orange-red mineral as Crocoite
in 1895, it had also been found in mines of the nearby
Luina, Waratah, Whyte River, and Zeehan districts. In
2000, the Honorable John Bestwick, minister of mines
of the Australian State of Tasmania, declared Crocoite
to be Tasmania’s official mineral.
From the Tsvetnoi mine, Mt. Uspenskaya, the Preobrazhensky
mine, and other mines, Beresovsk district, and on Mt.
Tochil’naya, Middle Ural Mountains, near Yekaterinburg
(Sverdlovsk), Russia. At Băiţa Mining District (Baita Bihor; Rézbánya),
Romania. In Germany, fine examples from Obercallenberg,
near Glauchau, Saxony. In the Hopeful vein, Leadhills,
Lanarkshire, Scotland. From the Greystone quarry, Lezant,
Cornwall, England. At the Cantonniers mine, Nontron,
Dordogne, France. From Howard’s Luck mine, Umtali, and
at a number of other minor occurrences in Zimbabwe.
From the Argent Pb–Zn mines, about 100 km east of Johannesburg,
Transvaal, South Africa. In Australia, as exceptional
specimens and an ore of lead in the Dundas district,
at the Adelaide, West Comet, and other mines, also from
the Heazlewood, Whyte River, and Magnet mines, Tasmania;
from the Happy Jack mine, Comet Vale, and several other
places in Western Australia; at the Wadnaminga gold
mines, near Olary, South Australia. From Labo, Luzon,
Philippines. At Goyabeira, near Congonhas do Campo,
Minas Gerais, Brazil. In the USA, from Darwin, Inyo
County, California; at the Moon Anchor, Potter-Kramer,
Pack Rat, and other mines south of Wickenburg, Maricopa