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9 Apr 2024: Zircon crystal structure (tetragonal), CrystalMaker. Zircon is a common accessory mineral of many igneous rocks. Pleochroic haloes are formed by damage to the crystal lattice of enclosing minerals by the radioactive decay of elements such as Th and

9 Apr 2024: Tourmaline crystal structure (trigonal), CrystalMaker. Tourmaline is the only common mineral of which boron is an essential constituent. Its presence in a rock, therefore, indicates that the rock contains significant boron. Formula.

9 Apr 2024: Sphene crystal structure, CrystalMaker. Formula. CaTi[SiO. 4. ](O, OH, F). Structure. Orthosilicate. Crystal System. Crystal system: monoclinic (). Physical Properties. Colour in hand specimen: colourless, yellow, green, brown or black. Cleavage: one

9 Apr 2024: Serpentine crystal lattice, with sheet silicate structure (CrystalMaker). Serpentine is a common alteration product of olivine, produced by hydration at low temperatures. Formula. Mg. 3. [Si. 2. O. 5. ](OH). 4. Structure. Sheet silicate. Crystal

9 Apr 2024: Quartz single crystal, no cleavage, conchoidal fracture. Quartz prisms, vitreous lustre. Quartz prisms (roughly hexagonal habit). Quartz crystal structure (trigonal unit cell), CrystalMaker. Formula. SiO. 2. Structure. Framework silicate. Crystal

9 Apr 2024: Pyrite crystals, with metallic lustre. Pyrite crystals within quartz. Pyrite cubis crystal structure, showing octahedral coordination of Fe by S. Formula. FeS. 2. Structure. Non-silicate. Crystal System. Crystal system: cubic. Physical Properties.

9 Apr 2024: Plagioclase feldspar. Plagioclase feldspar hand specimen, polycrystalline with opaque, white colour. Plagioclase feldspar with optical schiller. Plagioclase feldspar crystal structure, CrystalMaker. Formula. Na[AlSi. 3. O. 8. ] – Ca[Al. 2. Si. 2.

9 Apr 2024: Orthopyroxene. Orthopyroxene crystal structure, CrystalMaker. Orthopyroxene chemical variability. Enstatite (common in mafic rocks) always has high Mg and low Ca. Formula. (Mg,Fe). 2. Si. 2. O. 6. Structure. Chain silicate. Crystal System. Crystal

9 Apr 2024: Olivine hand specimen, no cleavage. Olivine crystal structure, CrystalMaker. Formula. (Mg,Fe). 2. [SiO. 4. ]. Structure. Orthosilicate. Crystal System. Crystal system: orthorhombic () (-). Physical Properties. Colour in hand specimen: pale green.

9 Apr 2024: Minerals. Rocks comprise minerals. In order to understand the paragenesis of a rock, be it igneous, sedimentary or metamorphic, we must identify its constituent minerals. The aim of this collection is to detail the structural, physical and optical