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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: Apatite crystal structure, CrystalMaker. Formula. Ca. 5. (PO. 4. ). 3. (OH,F,Cl). Structure. Non-silicate. Crystal System. Crystal system: hexagonal (-). Physical Properties. Colour in hand specimen: green, white, yellow, blue brown etc. Hardness: 5.

9 Apr 2024: Epidote crystal structure. Formula. Ca. 2. Al. 2. O(Al,Fe. 3+. )OH[Si. 2. O. 7. ][SiO. 4. ]. Structure. Orthosilicate. Crystal System. Crystal system: monoclinic (-). Physical Properties. Colour in hand specimen: green. Cleavage: one, perfect.

9 Apr 2024: Single crystal calcite hand specimen. Small calcite crystals growing from a free surface. Milky single crystal of calcite. Calcite crystal structure, CrystalMaker. Formula. CaCO. 3. Structure. Non-silicate. Crystal System. Crystal system: trigonal (-

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: Chlorite crystal structure, CrystalMaker. Formula. (Mg,Fe. 2+. ,Fe. 3+. ,Mn,Al). 12. [(Si,Al). 8. O. 20. ](OH). 16. Structure. Sheet silicate. Crystal System. Crystal system: monoclinic () (-). Physical Properties. Colour in hand specimen: green.

9 Apr 2024: Dolomite in hand specimen. Dolomite crystal structure, CrystalMaker. Formula. CaMg(CO. 3. ). 2. Structure. Non-silicate. Crystal System. Crystal system: trigonal (-). Physical Properties. Colour in hand specimen: white, often tinged with yellow or

9 Apr 2024: Fluorite crystal hand specimen, purple hue. Fluorite crystal structure (cubic), CrystalMaker. Formula. CaF. 2. Structure. Non-silicate. Crystal System. Crystal system: cubic. Physical Properties. Colour in hand specimen: extremely variable:

9 Apr 2024: Anhydrite crystal structure, CrystalMaker. Formula. CaSO. 4. Structure. Non-silicate. Crystal System. Crystal system: orthorhombic (). Physical Properties. Colour in hand specimen: white or colourless when pure. Cleavage: two at 90. Hardness: 3-3.5.

9 Apr 2024: Mica, muscovite. Crystals of muscovite with basal cleavage. Crystals of muscovite, colourless. Muscovite crystal structure (a sheet silicate), CrystalMaker. Formula. K. 2. Al. 4. [Si. 6. Al. 2. O. 20. ](OH,F). 4. Structure. Sheet silicate. Crystal

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: 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: Strongly pleochroic in reddish brown and pale straw. Often associated with small grains of an opaque accessory mineral, probably magnetite.

9 Apr 2024: Amphibole (hornblende). Amphibole hand specimen. Amphibole hand specimen. Formula. (Na,K). 0-1. Ca. 2. (Mg,Fe. 2+. ,Fe. 3+. ,Al). 5. Si. 6-7.5. Al. 2-0.5. O. 22. (OH). 2. Structure. Chain silicate. Crystal System. Crystal system: monoclinic () (-).

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: Mica, biotite. hand specimen of biotite mica. Crystals of bioitie mica with perfect basal cleavage. Biotite sheet silicate crystal structure, CrystalMaker. Formula. K. 2. (Mg,Fe. 2+. ). 6-4. (Fe. 3+. ,Al,Ti). 0-2. [Si. 6-5. Al. 2-3. O. 20. ](OH,F).

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: Alkali Feldspar. Alkali feldspar hand specimen, pink hue. Alkali feldspar hand specimen, milky white. Simply twinned alkali feldspar in granite. Alkali feldspar unit cell, CrystalMaker. Formula. (K,Na)[AlSi. 3. O. 8. ]. Structure. Framework

9 Apr 2024: Clinopyroxene (augite). Phase diagram deomstrating the chemical compositional range for clinopyroxenes. Formula. (Ca,Mg,Fe. 2+. ,Fe. 3+. ,Ti,Al). 2. [(Si,Al). 2. O. 6. ]. Structure. Chain silicate. Crystal System. Crystal system: monoclinic ().

9 Apr 2024: Bottryoidal hematite crystal. Hematite crystal strucutre, CrystalMaker. Formula. Fe. 2. O. 3. Structure. Non-silicate. Crystal System. Crystal system: trigonal (-). Physical Properties. Colour in hand specimen: black, steel-grey and bright to dull