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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: Browse Items (7 total). Tags: igneous. Sort by:. Formula Ca5(PO4)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 Optical

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: Magnetite. Title. Magnetite. Subject. Magnetite is the most abundant oxide in igneous rock. ... Silver-black. Metallic lustre. No cleavage. Rock Specimens. Mineral Name. magnetite. iron oxide.

9 Apr 2024: The olivine has decomposed to magnetite and serpentine. Relict olivine grains display characteristic curving cracks andClinopyroxene (augite). - ... Some simple twinning. Accessory minerals. - Opaque, interstitial, probably magnetite. Rock History.

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: 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: Some areof magnetite, clinopyroxene and other minerals. Extensive alteration along abundant cracks. ... Groundmass. - Fine-grained. Plagioclase feldspar needles, clinopyroxene, some olivine (mostly altered), and opaques, probably magnetite.

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: 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.