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2. Quartzite - Wikipedia

   en.wikipedia.org/wiki/Quartzite

   Quartzite is a very hard rock composed predominantly of an interlocking mosaic of quartz crystals. The grainy, sandpaper-like surface is glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization, causing streaks and lenses to form within the quartzite. [1 ...

3. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   Quartz. Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2. Quartz is, therefore, classified structurally as a framework silicate mineral ...

4. Llanite - Wikipedia

   en.wikipedia.org/wiki/Llanite

   Llanite. Llanite is a porphyritic rhyolite with distinctive phenocrysts of blue quartz (a rare quartz color) and perthitic feldspar (light grayish-orangeish). The brown, fine-grained groundmass consists of very small quartz, feldspar, and biotite mica crystals. Llanite comes from a hypabyssal porphyritic rhyolite dike that intrudes Precambrian ...

5. Dumortierite - Wikipedia

   en.wikipedia.org/wiki/Dumortierite

   Dumortierite quartz is blue colored quartz containing abundant dumortierite inclusions. Dumortierite was first described in 1881 for an occurrence in Chaponost, in the Rhône - Alps of France and named for the French paleontologist Eugène Dumortier (1803–1873). [5] It typically occurs in high temperature aluminium rich regional metamorphic ...

6. Sioux Quartzite - Wikipedia

   en.wikipedia.org/wiki/Sioux_quartzite

   Sioux Quartzite at Falls Park, Sioux Falls, South Dakota Cross-bedding in the Sioux Quartzite, Blue Mounds State Park, Minnesota, United States.. The Sioux Quartzite is a Proterozoic quartzite that is found in the region around the intersection of Minnesota, South Dakota, and Iowa, and correlates with other rock units throughout the upper midwestern and southwestern United States.

7. Larvikite - Wikipedia

   en.wikipedia.org/wiki/Larvikite

   Larvikite. Polished larvikite (marketed as "Blue Pearl Granite"), showing labradorescence, is a popular decorative stone. Larvikite is an igneous rock, specifically a variety of monzonite, [1] notable for the presence of thumbnail-sized crystals of feldspar. These feldspars are known as ternary because they contain significant components of all ...