Erythrite

Erythrite
Erythrite

Erythrite crystals
General
Category Arsenate mineral
Chemical formula Co3(AsO4)2·8H2O
Strunz classification 08.CE.40
Dana classification 40.03.06.03 Vivianite group
Identification
Color Crimson to peach-red, pale rose, or pink, may be zoned
Crystal habit Radial or stellate aggregates, fibrous, drusy; usually powdery and massive - rarely as striated prismatic crystals
Crystal system Monoclinic - Prismatic H-M Symbol (2/m) Space Group: 2/m
Cleavage Perfect on {010}; poor on {100} and {102}.
Tenacity Sectile
Mohs scale hardness 1.5 - 2.5
Luster Subadamantine, pearly on cleavages
Streak Pale red to pink
Diaphaneity Transparent to translucent
Specific gravity 3.06
Optical properties Biaxial (+)
Refractive index nα = 1.626 - 1.629 nβ = 1.662 - 1.663 nγ = 1.699 - 1.701
Birefringence δ = 0.073
Pleochroism Visible: X = pale pinkish to pale rose; Y = pale violet to pale violet-rose; Z = deep red
References [1][2][3]

Erythrite or red cobalt is a secondary hydrated cobalt arsenate mineral with the formula (Co3(AsO4)2·8H2O). Erythrite and annabergite (Ni3(AsO4)2·8H2O) (nickel arsenate) form a complete series with the general formula (Co,Ni)3(AsO4)2·8H2O.

Erythrite from Morocco


Erythrite crystallizes in the monoclinic system and forms prismatic crystals. The color is crimson to pink and occurs as a secondary coating known as cobalt bloom on cobalt arsenide minerals. Well-formed crystals are rare, with most of the mineral manifesting in crusts or small reniform aggregates.

Erythrite was first described in 1832 for an occurrence in Grube Daniel, Schneeberg, Saxony,[3] and takes its name from the Greek έρυθρος (erythros), meaning red.[2] Historically, erythrite itself has not been an economically important mineral, but the prospector may use it as a guide to associated cobalt and native silver.

Erythrite occurs as a secondary mineral in the oxide zone of Co–Ni–As bearing mineral deposits. It occurs in association with cobaltite, skutterudite, symplesite, roselite-beta, scorodite, pharmacosiderite, adamite, morenosite, retgersite, and malachite.[1]

Notable localities are Cobalt, Ontario; Schneeberg, Saxony, Germany; Joachimsthal, Czech Republic; Cornwall, England; Bou Azzer, Morocco; the Blackbird mine, Lemhi County, Idaho; Sara Alicia mine, near Alamos, Sonora, Mexico; Mt. Cobalt, Queensland and the Dome Rock copper mine, Mingary, South Australia.[1]

Other varieties

The nickel variety, annabergite, occurs as a light green nickel bloom on nickel arsenides. In addition iron, magnesium and zinc can also substitute for the cobalt position, creating three other minerals: parasymplesite (Fe), hörnesite (Mg) and kottigite (Zn).

References



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Look at other dictionaries:

  • Érythrite — Catégorie VIII : phosphates, arséniates, vanadates[1] Érythrite Bou Azzer Maroc (5.5x4.5 cm ; XX 1.7 cm) …   Wikipédia en Français

  • Erythrite — Érythrite Érythrite Catégorie VIII : phosphates, arséniates, vanadates Érythrite Bou Azzer Maroc (5.5x4.5cm; XX1.7cm) …   Wikipédia en Français

  • Erythrite — E*ryth rite, n. [Gr. eryqro s red.] 1. (Chem.) A colorless crystalline substance, {C4H6.(OH)4}, of a sweet, cooling taste, extracted from certain lichens, and obtained by the decomposition of erythrin; called also {erythrol}, {erythroglucin},… …   The Collaborative International Dictionary of English

  • erythrite — [er′i thrīt΄] n. [ ERYTHR(O) + ITE1] 1. ERYTHRITOL 2. a reddish or pinkish, very soft, monoclinic mineral, Co3 (AsO4) 2·8H2O, that usually forms as a crust near cobalt deposits; hydrous cobalt arsenate: cf. ANNABERGITE …   English World dictionary

  • erythrite — /i rith ruyt, er euh thruyt /, n. 1. a mineral, hydrous cobalt arsenate, Co3As2O8·8H2O, occurring as a powdery, usually red incrustation on cobalt minerals; cobalt bloom. 2. erythritol. [1835 45; ERYTHR + ITE1] * * * ▪ mineral also called  Cobalt …   Universalium

  • ÉRYTHRITE (chimie) — ÉRYTHRITE, chimie Polyol de formule:CH2OH CHOH CHOH CH2OH. Masse moléculaire: 122,12 g. Masse spécifique: 1,45 g/cm3. Point de fusion: 119 120 0C. Point d’ébullition: 331 0C. Corps polymorphe, cristallisé à partir de ses solutions aqueuses,… …   Encyclopédie Universelle

  • erythrite — noun Date: 1844 a usually rose colored mineral consisting of a hydrous cobalt arsenate occurring especially in monoclinic crystals …   New Collegiate Dictionary

  • erythrite — noun Red cobalt, a secondary hydrated arsenate of cobalt minerals with the formula (Co(AsO)·8HO) …   Wiktionary

  • erythrite — SYN: erythritol …   Medical dictionary

  • érythrite — (entrée créée par le supplément) (é ri tri t ) s. f. Terme de chimie. Principe sucré naturel, analogue à la glycérine …   Dictionnaire de la Langue Française d'Émile Littré

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