Aragonite

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Aragonite
Aragonite Salsigne France.jpg
Aragonite frae Salsignes Mine, Aude department, France Size: 30x30x20 cm
General
Category Carbonate mineral
Formula
(repeating unit)
CaCO3
Strunz classification 05.AB.15
Crystal symmetry Orthorhombic (2/m 2/m 2/m) - dipyramidal
Unit cell a = 4.95 Å, b = 7.96 Å, c = 5.74 Å; Z = 4
Identification
Color White, reid, yellae, orange, green, purpie, grey, blue an broun
Crystal habit Pseudohexagonal, prismatic crystals, acicular, columnar, globular, reniform, pisolitic, coralloidal, stalactitic, internally bandit
Crystal seestem Orthorhombic
Twinnin Polysynthetic parallel tae {100} cyclically on {110}
Cleavage Distinct on {010}, imperfect {110} an {011}
Fractur Subconchoidal
Tenacity Brittle
Mohs scale hairdness 3.5-4
Luster Vitreous, resinous on fracture surfaces
Streak White
Diaphaneity Translucent tae transparent
Specific gravity 2.95
Optical properties Biaxial (-)
Refractive index nα = 1.529 - 1.530 nβ = 1.680 - 1.682 nγ = 1.685 - 1.686
Birefringence δ = 0.156
2V angle 18°
Solubility Dilute acid
Ither characteristics Fluorescence: pale rose, yellae, white or bluish; phosphorescence: greenish or white (LW UV); yellaeish (SW UV)
References [1][2][3]

Aragonite is a carbonate mineral, ane o the twa common, naiturally occurrin, crystal furms o calcium carbonate, CaCO3 (the ither furm bein the mineral calcite). It is furmed bi biological an pheesical processes, includin precipitation frae marine an freshwatter environments.

Aragonite's crystal lattice differs frae that o calcite, resultin in a different crystal shape, an orthorhombic seestem wi acicular crystals. Repeatit twinnin results in pseudo-hexagonal furms. Aragonite mey be columnar or fibrous, occasionally in branchin stalactitic furms cried flos-ferri ("flouers o airn") frae thair association wi the ores at the Carinthian airn mines.

References[eedit | eedit soorce]