What is Spilitic lava?
Spilite is formed when basaltic lava reacts with seawater, or from hydrothermal alteration when seawater circulates through hot volcanic rocks.
Is dolerite an igneous?
Dolerite is an igneous rock, that is, rock initially molten and injected as a fluid into older sedimentary rocks. The magma, of quartz tholeiite composition, was emplaced as a liquid which rose upwards through the basement rocks into older sedimentary rocks of the Parmeener Supergroup.
What is dolerite and how is it formed?
Dolerite sills and dykes are intrusions of igneous rock formed by molten magma from the Earth’s mantle, which forced its way to the surface through cracks in the rock layers. Cracks may form when there is tension in the Earth’s surface, e.g. the break-up of Gondwanaland.
What is Microgabbro?
Microgabbro is a medium-grained intrusive igneous rock. It contains crystals, smaller than rice grains, which are interlocking and randomly oriented. It is dark green to dark grey, with occasional rare paler crystals. How is it formed? Dolerite is the medium-grained equivalent of gabbro.
What type of igneous rock is dolerite?
diabase, also called Dolerite, fine- to medium-grained, dark gray to black intrusive igneous rock. It is extremely hard and tough and is commonly quarried for crushed stone, under the name of trap.
What’s the difference between granite and dolerite?
As nouns the difference between dolerite and granite is that dolerite is (geology) a fine-grained basaltic rock while granite is granita (sorbet).
What is a spilite rock?
spilite, fine-grained or dense, extrusive igneous (volcanic) rock that is usually free of visible crystals and is commonly greenish or grayish green in colour. Spilites are of basaltic character but contain the feldspar albite in place of the normal labradorite. The dark mineral is a pale-brown spilite | rock | Britannica BrowseSearch
What does spilite look like?
spilite, fine-grained or dense, extrusive igneous (volcanic) rock that is usually free of visible crystals and is commonly greenish or grayish green in colour. Spilites are of basaltic character but contain the feldspar albite in place of the normal labradorite. The dark mineral is a pale-brown
Who coined the term spilite?
The term was introduced into the geological literature by Alexandre Brongniart in 1827. Spilite is formed when basaltic lava reacts with seawater, or from hydrothermal alteration when seawater circulates through hot volcanic rocks.
What is the difference between augite and spilite?
The dark mineral is a pale-brown augite; spilites are, however, usually decomposed, and augite is represented by chlorite and calcite. Spilites are often blistered or pocked and show a wonderfully preserved pillow structure, a feature in most cases indicative of lavas of submarine origin.