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2. Vein (geology) - Wikipedia

   en.wikipedia.org/wiki/Vein_(geology)

   Vein (geology) White veins in dark rock at Imperia, Italy. In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation. The hydraulic flow involved is usually due to hydrothermal circulation. [1]

3. Howlite - Wikipedia

   en.wikipedia.org/wiki/Howlite

   The nodules are white with fine grey or black veins in an erratic, often web-like pattern, opaque with a sub-vitreous luster. The crystals at Iona are colorless, white or brown and are often translucent or transparent. Its structure is monoclinic with a Mohs hardness of 3.5 and lacks regular cleavage. Crystals are prismatic and flattened on ...

4. 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 ...

5. Pegmatite - Wikipedia

   en.wikipedia.org/wiki/Pegmatite

   Pegmatite. A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite.

6. Serpentine subgroup - Wikipedia

   en.wikipedia.org/wiki/Serpentine_subgroup

   Colors range from white to grey, yellow to green, and brown to black, and are often splotchy or veined. Many are intergrown with other minerals, such as calcite and dolomite. The basic structural unit of serpentine is a polar layer 0.72 nm thick.

7. Mottramite - Wikipedia

   en.wikipedia.org/wiki/Mottramite

   Mottramite is the commonest of them. It occurs as black elongated boat shaped crystals up to about one mm long, scattered over white vein quartz. Occasionally, crusts of mottramite occur in cavities in the quartz that appear to have been formed by the dissolution of baryte. Mottramite was almost certainly produced by oxidation of galena. [15]