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Aragonite frae Salsignes Mine, Aude department, France Size: 30x30x20 cm
CategoryCarbonate mineral
(repeatin unit)
Strunz clessification05.AB.15
Creestal seestemOrthorhombic
Space groupOrthorhombic (2/m 2/m 2/m) - dipyramidal
Unit cella = 4.95 Å, b = 7.96 Å, c = 5.74 Å; Z = 4
ColourWhite, reid, yellae, orange, green, purpie, grey, blae an broun
Creestal habitPseudohexagonal, prismatic crystals, acicular, columnar, globular, reniform, pisolitic, coralloidal, stalactitic, internally bandit
TwinninPolysynthetic parallel tae {100} cyclically on {110}
CleavageDistinct on {010}, imperfect {110} an {011}
Mohs scale haurdness3.5-4
SkinkleVitreous, resinous on fracture surfaces
DiaphaneityLeamin tae skyre
Speceefic gravity2.95
Optical propertiesBiaxial (-)
Refractive indexnα = 1.529 - 1.530 nβ = 1.680 - 1.682 nγ = 1.685 - 1.686
Birefringenceδ = 0.156
2V angle18°
SolubilityDilute acid
Ither chairacteristicsFluorescence: fauch rose, yellae, white or blaeish; phosphorescence: greenish or white (LW UV); yellaeish (SW UV)

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.

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