Obsidian and Coal Definition

Definition of Obsidian and Coal

The general Obsidian and Coal definition can be stated as: Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth. On the other hand, Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers called coal beds. Along with definition of Obsidian and Coal, get to know about Properties of Obsidian and Coal. Get to know more information about Obsidian and Coal origin and discoverer, etymology and class.

History of Obsidian and Coal

The history of Obsidian and Coal gives information about where the rock was found and who was its discoverer. Almost each and every aspect of Earth's history is recorded in rocks be it the volcanoes which were erupted or the plants, animals and organisms which are now extinct, as rocks are present from millions of years.

Obsidian and Coal Origin and Discoverer

Obsidian and Coal definition gives us a brief idea about the two rocks. In some cases, the definition also gives summary about the Formation of Obsidian and Coal. In this section, you will know about Obsidian and Coal Origin and Discoverer. Origin of Obsidian is Ethiopia whereas Origin of Coal is USA. It is interesting to know the name of Obsidian and Coal discoverer. The Discoverer of Obsidian is Obsius and the discoverer of Coal is John Peter Salley.

Etymology of Obsidian and Coal

Along with Obsidian and Coal definition, know more about the etymology of Obsidian and Coal. Etymology of Obsidian and Coal gives information about origin and formation of a particular rock. Know more about Formation of Obsidian and Formation of Coal. The etymology of Obsidian is From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius while that of Coal is From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius. The process of formation of rocks defines the class of rock. All the rocks in a class are formed by similar processes. Obsidian belongs to Igneous Rocks while Coal belongs to Sedimentary Rocks. The sub-class, group and other categories of Obsidian and Coal are listed below.

For Obsidian,

• Sub-class: Durable Rock and Medium Hardness Rock
• Group: Volcanic
• Other Categories: Opaque rock

For Coal,

• Sub-class: Durable Rock and Soft Rock
• Group:
• Other Categories: Coarse grained rock, Fine grained rock, Medium grained rock and Opaque rock