| labradorite |
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noun (plural: labradorites)
- (mineralogy) A plagioclase feldspar, the fourth member of the Albite-Anorthite solid solution series. Often very coarsely crystalline, it is used as a decorative stone for carvings and building faí§ades. Crystal surfaces often show a bluish reflection called "Schiller", which resembles the reflections from a butterfly's wing.
- Chemical composition: Calcium sodium aluminum silicate, <math>Ca_xNa_xAlSi_3O_8</math>
- Physical properties:
Moh's Hardness: 6.0
Specific gravity: 2.71
Color: Usually bluish-gray to dark gray
Luster: glassy
Fracture: conchoidal
Cleavage: two good at about 94º to each other
- Habit: Triclinic - pinacoidal. Crystals are common and usually striated.
| | | lamina |
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noun (pl1=laminaspl2=laminae)
- (anatomy) A thin plate or scale, such as the arch of a vertebra.
- (botany) The flat part of a leaf or leaflet; the blade.
| | langbeinite |
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noun - (mineralogy) a saline evaporite, consisting of a mixed potassium and magnesium sulphate
| | laumontite |
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noun
- (mineralogy) A mineral, of a white color and vitreous luster. It is a hydrous silicate of alumina and lime. Exposed to the air, it loses water, becomes opaque, and crumbles.
| | lazurite |
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noun Lazurite
- (mineralogy) A mineral of metamorphosed limestones. Lazurite forms the gemstone lapis lazuli, and crushed lazurite provided the ultramarine color in artists' paint of the old masters. sodalite and lazurite form the sodalite group of silicate minerals.
- Chemical composition: Sodium aluminum silicate with sulphur, <math>Na_{4-5}Al_3Si_3O_{12}S</math>
| | leucite |
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noun
- (mineralogy) A mineral of silica-poor igneous, plutonic and volcanic rocks. Chemically, Leucite is a potassium feldspar with insufficient silica to satisfy the chemical bonds. Because of the unfilled bonds, Leucite weathers rapidly and can only be seen as inclusions in freshly broken rock.
- Chemical composition: Potassium aluminum subsilicate, <math>KAlSi?_2O_6</math>
- Physical properties:
Moh's Hardness: 5.5-6.0
Specific gravity: 2.4-2.5
Color: Gray to white to colorless
Luster: Glassy, but rapidly weathers to a dull surface
Fracture: Conchoidal
Cleavage: Imperfect dodecahedral
- Habit: Tetragonal-trapezohedral (pseudo-isometric)
| | limonite |
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noun - (mineralogy) any of several natural hydrous iron oxides; often a mixture of goethite and hemite with clays and manganese oxide
| | loadstone |
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noun
- (context, archaic) A magnet, iron oxide in the form of w:magnetite, magnetite.
| | lodestone |
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noun - A naturally occuring magnet.
- An obsolete term for the mineral magnetite.
| | luster |
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noun
- (alternative spelling of, lustre) shine, Shine, polish, or sparkle.
- He polished the brass doorknob to a high .
- By extension, interest, attractiveness, or splendor.
- After so many years in the same field, the job had lost its .
- Refinement, polish, or quality.
- He spoke with all the lustre a seasoned enthusiast should have.
- A period of five years, from the Latin word lustrum
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