Obsidian Rock – Meaning, Uses, Facts, Properties & Color

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Obsidian Rock
Meaning, Uses, Facts, Properties Color

• From- WorldofstonesUSA

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Introduction

• We know three main classes of rocks, sedimentary,
  igneous, and metamorphic. In the Limestone
  article, we learned how sedimentation occurs and
  the formation of sedimentary rocks takes place.
  Today, we are going to know Obsidian rock, which
  falls in the main class of igneous rocks.
• We know igneous rocks have two basic types
• 1. Intrusive Igneous Rocks
• 2. Extrusive Igneous Rocks

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Intrusive Igneous Rocks

• When molten lava/magma is cooling slowly below
  the surface of the earth and forms large crystals
  in the rocks, they are known as intrusive igneous
  rocks. For example-
• Diorite
• Gabbro
• Granite
• Pegmatite
• Peridotite

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Extrusive Igneous Rocks

• When molten magma is cooling rapidly onto the
  surface of the earth and forms small crystals in
  the rocks, they are known as extrusive igneous
  rocks. For example-
• Obsidian
• Andesite
• Basalt
• Dacite
• Pumice
• Rhyolite
• Scoria
• Tuff
• Fire Opal

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What is Obsidian Rock ?

• Obsidian is a glassy igneous rock that comes in a
  wide range of colours and textures. It forms when
  felsic lava extruded from a volcano onto the
  surface of the earth.
• The cooling of lava takes place so rapidly that
  no chance remains for proper crystallization
  (Atomic Arrangements) and finds as an amorphous
  glass material. It has a smooth and uniform
  texture, which breaks with a conchoidal fracture.

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Geological Classification of Obsidian Rock ?

• Lets see the classification of obsidian rocks
  from the perspective of a geologist.
• Class Igneous Rocks Sub-Class Medium Hardness
  Rocks
• Family-Group Volcanic
• Category Opaque Rocks
• Alternate Names Lava, Glassy Lava, Xaga, Royal
  Agate, Glass Agate, Volcanic Glass, Glass Gem,
  Guardian Gem, and Black Beauty

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Formation of Obsidian Rocks in Nature

• We have seen in the earlier section that obsidian
  is a type of extrusive rock. It forms on the
  surface of the earth when magma or lava comes out
  due to volcanic phenomena and rapid cooling takes
  place. Obsidian rock can form in a variety of
  cooling environments such as-
• Along the edges of a flow of magma or lava
• Along the edges of a dome of the volcano
• Along the edges of a sill or dike, which takes
  place under the surface and it is the only
  intrusive type
• The point where magma comes into contact with
  water on the surface
• The point where magma cools due to airborne
  cooling effects

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Properties of Obsidian
Specific Gravity Density of Obsidian

• Obsidians have various physical visual
  properties, such as Hardness, Grain Size,
  Fracture, Streak (Colors), Porosity, Luster, and
  Strength. These all property attributes determine
  the applications of obsidian rocks. Lets see
  some significant properties of obsidians.

• The density of rock is used to express specific
  gravity. It is measured in relevance to the
  density of water in gram per cubic centimeter of
  the mass. The density of obsidian is 2.55 g/cubic
  cm. It means it is heavier than water and dense
  medium as a mass.

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Streaks Colors of Obsidian

• The streak of obsidian is white, but various
  colors occur in nature.
• Frequently found colors of Obsidian rocks are
• The highest occurrence of obsidians is in Black,
  but it is also available in Brown, Green, or Tan.
• Rarely found colors of Obsidian rocks are
• A very rare occurrence of obsidians is Blue,
  Orange, Red, and Yellow.
• The occurrence of color is due to the presence of
  different trace elements in obsidian rocks.

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Compressive Strength of Obsidian

• When a compressive pressure (In Newton unit) is
  applied to the rocks, a permanent deformation of
  rocks takes place at a point of pressure. It is
  termed as the compressive strength of rocks and
  obsidians fractured or permanently deformed at
  0.15 N per square millimeter. It means obsidian
  is easy to break and chipped by some impacts. It
  also renders obsidian the unfit stone for rings
  and bracelets like jewelry production.

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Wrapping it Up

• In the series of identifying various rocks and
  natural stones at World of Stones, USA, we have
  explored different aspects of obsidian rocks such
  as meaning, uses, facts, properties, and colors
  of obsidian edge Stones, USA is an excellent
  place to buy a variety of natural rocks used
  primarily for exterior applications in the
  building construction industry. If you are
  interested to know about rocks and stones,
• keep reading blogs at World of Stones.

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Contact Us

• World of Stones USA
• Address-
• 18238 Showalter Road, Hagerstown, Maryland 21742,
  United States
• Phone No- [phone]
• Email- info_at_worldofstonesusa.com
• Website- www.worldofstonesusa.com

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Thank You

• By- Worldofstones USA