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Crocoite

This page kindly sponsored by PH, dedicated to JULIA ROSE HUGGINS
Formula:
Pb(CrO4)
System:
Monoclinic
Colour:
Orange, red, yellow; ...
Lustre:
Sub-Adamantine, Sub-Vitreous, Resinous, Waxy
Hardness:
2½ - 3
Name:
Originally recognized by Mikhail Vassil’evich Lomonosov in 1763 as a red lead ore. Johann Gottlob Lehmann in 1766 named it Nova Minera Plumbi. Various authors later gave the mineral a name signifying the presence of lead and the color red: minera plumbi rubra (Wallerius, 1778), Rothes bleierz (Werner, 1774), and Plomb rouge (Macquart, 1789). After the element chromium was announced in 1798, a new series of names was applied to the species: Plomb chromaté (Haüy, 1801), Kallochrom (Hausmann, 1813), etc. Re-named Crocise by François Sulpice Beudant in 1832 and Krokoisite by Franz von Kobell in 1838. Translated to the current pronunciation, Krokoit, by Johann August Breithaupt in 1841. Named Beresofite in 1844 by Charles Upham Shepard. Named Lehmannite in by Henry J. Brooke and William H. Miller in 1852. The name crocite comes from the Greek κρόκος "crocon" = saffron, alluding to the saffron-orange color of its powder.
Crocoite is commonly found as crystals, usually as long prismatic crystals and more rarely as equant crystals, but are most often poorly terminated, and are usually of a bright hyacinth-red color, which are translucent and have an adamantine to vitreous lustre. When fine grained it can be bright yellow to orange, and some crystals are dark red.

Visit gemdat.org for gemological information about Crocoite.

Classification of Crocoite

Approved, 'Grandfathered' (first described prior to 1959)
7.FA.20

7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
F : Chromates
A : Without additional anions
Dana 7th ed.:
35.3.1.1
35.3.1.1

35 : ANHYDROUS CHROMATES
3 : AXO4
27.2.5

27 : Sulphites, Chromates, Molybdates and Tungstates
2 : Chromates
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Type Occurrence of Crocoite

Place of Conservation of Type Material:
Natural History Museum, Paris

Occurrences of Crocoite

Geological Setting:
Uncommon secondary mineral in lead deposits associated with chromium bearing rocks.

Physical Properties of Crocoite

Sub-Adamantine, Sub-Vitreous, Resinous, Waxy
Diaphaneity (Transparency):
Transparent, Translucent
Colour:
Orange, red, yellow; orange-red in transmitted light.
Streak:
Yellow-orange
Hardness (Mohs):
2½ - 3
Tenacity:
Brittle
Cleavage:
Poor/Indistinct
Distinct on {110}, indistinct on {001} and {100}.
Fracture:
Conchoidal
Density:
5.97 - 6.02 g/cm3 (Measured)    5.97 g/cm3 (Calculated)
Comment:
6.06 (Dundas mat.); 6.12 (artificial mat.)

Crystallography of Crocoite

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
P21/b
Cell Parameters:
a = 7.12Å, b = 7.421Å, c = 6.8Å
β = 102.41°
Ratio:
a:b:c = 0.959 : 1 : 0.916
Unit Cell Volume:
V 350.90 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals commonly prismatic [001] to acicular crystals with nearly square outline; elongated parallel to [_101]; pseudo-octahedral at times, with {111} {_111}, or acute rhombohedral with {110} {_hOl}. Faces usually smooth and brilliant; {110} commonly striated [001], and the steep orthodomes rounded or distorted. Crystals are often cavernous or hollow. Massive; imperfectly columnar to granular.

Crystallographic forms of Crocoite

Crystal Atlas:
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Click on an icon to view
Crocoite no.76 - Goldschmidt (1913-1926)
Crocoite no.111 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

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Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Optical Data of Crocoite

Type:
Biaxial (+)
RI values:
nα = 2.290(2) nβ = 2.360(2) nγ = 2.660(2)
2V:
Measured: 57° , Calculated: 54°
Max Birefringence:
δ = 0.370
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Very High
Dispersion:
very strong r > v inclined
Pleochroism:
Weak
Comments:
X= Red-orange
Y = b = Red-orange
Z ^c +5½° = Blood red

Chemical Properties of Crocoite

Formula:
Pb(CrO4)
All elements listed in formula:
Common Impurities:
Zn,S

Relationship of Crocoite to other Species

27.2.1TarapacáiteK2(CrO4)
27.2.2LópeziteK2Cr2O7
27.2.3ChromatiteCaCr6+O4
27.2.4HashemiteBa(CrO4)
27.2.6PhoenicochroitePb2(CrO4)O
27.2.7SantanaitePb11(CrO4)O12
27.2.8IranitePb10Cu(CrO4)6(SiO4)2(OH)2
27.2.9HemihedritePb10Zn(CrO4)6(SiO4)2(F,OH)2

Other Names for Crocoite

Other Information

Not fluorescent in UV
Health Risks:
Chromate minerals contain the carcinogenic and mutagenic chromate ion. Always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Do not pour chromate-containing solutions down the drain.

References for Crocoite

Reference List:
Lomonosov, Mikhail Vassil’evich (1763) Grundlagen der Metallurgie: 1: 44. [as Red lead-ore from Beresov]
Lehmann, Johann G.
(1766) Nov. Comm. Ac. Petrop. [as Nova minera Plumbi]
Lehmann, Johann G. (1767) Nachricht von einem neu endechten Bleyerze. Neues Hamburg Magazin: 7: 336-348.
Pallas (1770) Reise durch versch. Prov. russ. Reichs: 2: 235. [as Minerai de plomb rouge]
Werner, Abraham Gottlieb (1774) Von d. äusserlichen Kennzeichen d. Fossilien. Leipzig: 296. [as Rotbleierz and Rothes Bleierz]
Wallerius, J. G. (1775) Systema mineralogicum. Holmiae. vol. 2: 309. [as Minera Plumbi rubra]
Macquart, Louis Charles Henri (1789) Le Journal de physique et le radium, Paris: 36: 389. [as Plombe rouge de Sibérie]
Marquart, Louis Charles Henri (1789) Essais ou Recueil de mémoires sur plusieurs points de minéralogie, Chez Cechet, Paris, pp. 580 + 7 plates.
Vauquelin, Louis (1794) Le Journal de physique et le radium, Paris: 45: 393. [as Plombe rouge de Sibérie]
Vauquelin, Louis (1798) Le Journal de physique et le radium, Paris: 46: 152, 311. [as Plombe rouge de Sibérie]
Haüy, Rene Just (1801) Traité de minéralogie. First edition: in 4 volumes with atlas in fol.; also (1801), Paris: 3: 357. [as Plomb chromaté]
Hausmann, J. F. L. (1813) Handbuch der Mineralogie 3 volumes, Göttingen: 1084. [as Kallochrom]
Beudant, F. S. (1832) Crocoïse, plomb chromaté. Traité Élémentaire de Minéralogie, second edition, 2 volumes: 2: 669. [as Crocoise]
von Kobell, F. (1838) Grundzüge der Mineralogie. Nürnberg: 282. [as Krokoisit]
Breithaupt, A. (1841) Vollständige Handbuch der Mineralogie. Vol. 2: 262. [as Bleiischer Chromspath]
Brooke, H. J., Miller, W. H. (1852) Introduction to Mineralogy by William Phillips, London, 1823. New edition by Brooke and Miller. 8vo, London: 557. [as Lehmannite]
Shepard, Charles U. (1844) Treatise on Mineralogy. second edition: 121. [as Beresofite]
Dauber (1860) Königliche Akademie der Wissenschaften, Vienna, Ber.: 42: 19.
Des Cloizeaux (1882) Bulletin de la Société française de Minéralogie: 5: 103.

de Schulten
(1904) Bulletin de la Société française de Minéralogie: 27: 135.
Anderson, C. (1906) Mineralogical Notes: No. III - Axinite, petterdite, crocoite, datolite. Records of the Australian Museum: 6(3), 133-144.
Larsen, Esper S. (1921) The Microscopic Determination of the Nonopaque Minerals, First edition, USGS Bulletin 679: 63.
Goldschmidt, V. (1922) Atlas der Krystallformen. 9 volumes, atlas, and text: vol. 7: 130.
Hintze, C. (1929) Handbuch der Mineralogie. Berlin and Leipzig. 6 volumes: 1 [3B]: 4030.
Brill (1931) Zeitschrift für Kristallographie, Mineralogie und Petrographie: 77: 506.
Gliszczynski (1939) Zeitschrift für Kristallographie, Mineralogie und Petrographie: 101: 1.
Palache, C., Berman, H., Frondel, C. (1951) The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124pp.: 646-649.
Quareni, S., de Pieri, R. (1965) A 3-dimensional refinement of structure of crocoite (PbCrO4). Acta Crystallographica: 19: 287-289.
Wilkins, R. W. T (1971) The Raman spectrum of crocoite. Mineralogical Magazine: 38: 249-250.
Effenberger, H., Pertlik, F. (1986) Four monazite type structures: comparison of SrCrO4, SrSeO4, PbCrO4 (crocoite), and PbSeO4. Zeitschrift für Kristallographie: 176: 75-83.
Anthony, J. W., Bideaux, R. A., Bladh, K. W., Nichols, M. C. (2003) Handbook of Mineralogy, Volume V. Borates, Carbonates, Sulfates. Mineral Data Publishing, Tucson, AZ, 813pp.: 167.

Internet Links for Crocoite

Specimens:
The following Crocoite specimens are currently listed for sale on minfind.com.

Localities for Crocoite

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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