Selected Minerals – Today: Azurite

Azurite

• named after the color azure, a variation of blue that is often
  described as the color of the sky
• one of the two basic copper(II) carbonate minerals, the other being malachite
• Formula: Cu₃(CO₃)₂(OH)₂
• Space group: P2₁/c (No. 14)
• Crystal system: monoclinic
• Crystal class: 2/m
• Lattice parameters: a = 5.01 Å, b = 5.58 Å, c = 10.35 Å, α = 90°, β = 92.4°, γ = 90°

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Picture: Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Crystal structure (click on the picture to download the VESTA file):

CO₃ triangles (black), CuO₅ tetragonal pyramids (yellow)

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Selected Minerals – Today: Aragonite

Aragonite

• Named after the type locality Aragon (Spain)
• One of the two naturally occuring forms of calcium carbonate (the other being calcite)
• Formula: CaCO₃
• Space group: Pmcn (No. 62)
• Crystal system: orthorhombic
• Crystal class: mmm
• Lattice parameters: a = 4.95 Å, b = 7.96 Å, c = 5.74, α = β = γ = 90°

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Picture: Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Crystal structure (click on the picture to download the VESTA file):

CO₃ triangles (black), CaO₉ irregular polyhedra (blue)

Selected Minerals – Today: Anglesite

Anglesite

• Named after the type locality (a locality, where a a particuliar mineral was first found/identified), which is here the Isle of Anglesey (Wales)
• Occurs as an oxidation product of primary lead sulfide (PbS, Galena) ore
• Formula: PbSO₄
• Space group: Pnma (No. 62)
• Crystal system: orthorhombic
• Crystal class: mmm
• Lattice parameters: a = 8.48 Å, b = 5.40 Å, c = 6.96, α = β = γ = 90°

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Picture: Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Crystal structure (click on the picture to download the VESTA file):

SO₄ tetrahedra (yellow), PbO₈ irregular polyhedra (gray)

Selected Minerals – Today: Adamite

Adamite

• Named after the French mineralogist Gilbert-Joseph Adam (1795 – 1881)
• Typically occuring in weathered zones above zink ores
• Formula: Zn₂(OH)(AsO₄)
• Space group: Pnnm (No. 58)
• Crystal system: orthorhombic
• Crystal class: mmm
• Lattice parameters: a = 8.30 Å, b = 8.51 Å, c = 6.04, α = β = γ = 90°

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Picture: Rob Lavinsky, iRocks.com – CC BY-SA 3.0

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Crystal structure (click on the picture to download the VESTA file):

AsO₄ tetrahedra (green), ZnO₆ octahedra (gray)