Hobbies And Interests
Nebulite and Granulite
Nebulite is found in Precambrian shields, stable parts of the earth's crust laid down 4,600 million years ago. Its color ranges from light to dark gray and it's used locally as building material. It can also be polished for ornamental purposes. Granulite is also felsic and one of its essential ingredients, besides quartz, is garnet. It also has accessories like rutile, spinet, magnetite and corundum, the second hardest mineral after diamond. Accessories are minerals whose presence aren't essential to the definition of a rock. Granulite is found in Scandinavia, Canada, the United States and northwest Scotland. It's used as a construction material and is sometimes slabbed and polished.
Alkaline Felspar Rhyolite and Obsidian
Alkaline felspar rhyolite is an intrusive igneous rock, created in a volcano. Its accessories can be olivine, glass and magnetite. Its color depends on what it's made of and can range from white to dark green or black. It's found in Africa, the United States and Scandinavia. Though it's an interesting rock, it has no industrial or commercial use. Obsidian is a felsic rock that's also a form of glass. It's created from the rapid cooling of magma, and sometimes comes in long strands known as Pele's hair. In prehistoric times obsidian was used for tools and sculptures. Now it's used to make rock wool.
Granophyre, Pegmatite, Aplite
Granophyre is a light-colored rock that's sometimes reddish. It comes from veins within a volcano and is found all over the world where volcanic activity is or was. It's used as a building stone or ornamental gravel for parks or gardens. Pegmatite is also an igneous rock of quartz and alkaline feldspar. Its accessories can be tourmaline, beryl, topaz, zircon, apatite and other rare minerals and its color also depends on what it's made of, though it's usually light colored. In the United States beautiful pegmatite crystals are found in Maine; Massachusetts; Connecticut; Pikes Peak, Colorado; and the Black Hills of South Dakota. Aplite is white or light gray, with a fine or wavy grain. It's very pretty but has no commercial value.
Ignimbrite, Mylonite, Embrechite
Ignimbrite is a pyroclastic rock that contains consolidated glass and often bits of sedimentary rocks. It's light gray or brownish, and sometimes reddish or purple from oxidation. It's formed when hot ash rolls down the slopes of a volcano and consolidates quickly. It's widespread but found especially in New Zealand, Asia, Armenia and the Caribbean. Locally, it's used as building material. The components of mylonite are variable. It's a metamorphic rock. Under a microscope it appears as layers, strips and folds of minerals. It's associated with earthquakes and can be found along the San Andreas fault among other places. It's of no commercial use. Embrechite looks somewhat like marble or granite, and is light with dark streaks or markings. It's found in Finland, Canada, France's Massif Central and the Scottish highlands. Locally, it's used as a building stone.