{"id":1741,"date":"2014-09-16T16:24:48","date_gmt":"2014-09-16T16:24:48","guid":{"rendered":"https:\/\/waltonsons.com\/wp\/?page_id=1741"},"modified":"2014-10-31T05:18:06","modified_gmt":"2014-10-31T05:18:06","slug":"basalt","status":"publish","type":"page","link":"https:\/\/waltonsons.com\/?page_id=1741","title":{"rendered":"Basalt"},"content":{"rendered":"

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\"Basalt<\/p>\n

Basalt is a common extrusive igneous rock.\u00a0 It is a dark volcanic rock formed when mafic magmas reach the Earth\u2019s surface and flow across the landscape.\u00a0 Mafic means that basalt is magnesium-rich and silica-poor.\u00a0 Sometimes gases in the molten magma have not had time to escape and form bubbles or vesicles in the rock, making a porous or vesicular texture called scoria<\/i>.\u00a0 It is usually grey to black but rapidly weathers to brown or rust-red due to oxidation of its iron-rich minerals into rust.\u00a0 Basalt is high density and is fairly hard being equal to the mineral, quartz<\/i>.\u00a0 It is generally used in construction as building blocks.\u00a0 Columnar basalt<\/i> is used for making cobblestones.<\/p>\n

Bluestone<\/b>.\u00a0 The common commercial name of “bluestone<\/i>” is applied to a variety of building stones. Basalt in Victoria, Australia and in New Zealand is called bluestone<\/i>.\u00a0 The dolorite<\/i> of Stonehenge in Britain is also called bluestone.\u00a0 (Diabase<\/i> or dolerite is very similar to basalt.)<\/p>\n

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Black Granite<\/b>.\u00a0 Some dark colored igneous rocks, which are actually basalt, gabbro, dionite, <\/i>diabase <\/i>and anorthosite<\/i>, are quarried and sold as “black granite<\/i>.” \u00a0These stones contain little or no quartz or alkali feldspars, but, for all practical purposes, they are used interchangeably with true granites.<\/p>\n

\"Black<\/p>\n

Theoleitic basalt<\/i> is rich in silica and poor in sodium whereas Alkali basalt<\/i> is the reverse \u2014 poor in silica and rich in sodium.\u00a0 Alumina basalt<\/i> is high in alumina<\/i> and Boninite basalt<\/i> is high in magnesium.<\/p>\n

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The most famous basalt flow in the world is the Giant\u2019s Causeway<\/i> on the northern coast of Ireland.\u00a0 Natural geological formations of native Oregon columnar basalt can be seen along the Columbia River.\u00a0 A famous example of buildings constructed with basalt blocks is the ancient city of Ummel-Jimal<\/i> in Southern Syria. Basalt columns in western Scotland inspired the entrance to the world famous Waterhouse Building<\/i>, a London landmark.<\/p>\n

PHOTOS:<\/strong><\/p>\n