Definition
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
Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles
Discoverer
Obsius
Unknown
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From German Schalstein laminated limestone, and Schalgebirge layer of stone in stratified rock. From Old English scealu in its base sense of- thing that divides or separate,
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Group
Volcanic
Not Applicable
Other Categories
Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Glassy
Clastic, Splintery
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Black, Brown, Buff, Green, Grey, Red, Yellow
Durability
Durable
Durable
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone, Office Buildings
Other Architectural Uses
Not Yet Used
Curbing
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Medical Industry
Surgery
Not Yet Used
Antiquity Uses
Artifacts, Jewellery
Artifacts, Sculpture
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Creating Artwork, Pottery
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale
Features
Blocks negativity, Helps to protect against depression
Easily splits into thin plates, Generally rough to touch, Very fine grained rock
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Jantar Mantar in India
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Figurines
Not Yet Used
Used
Formation
When the lava is released from volcano, it undergoes a very rapid cooling which freezes the mechanisms of crystallization. The result is a volcanic glass with a uniform smooth texture.
Shale forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are later compacted hence forming shale.
Mineral Content
Not Available
Albite, Biotite, Calcite, Chert, Chlorite, Dolomite, Hematite, Micas, Muscovite or Illite, Pyrite, Quartz, Silica, Sulfides
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, Fe, Mg, Silicon Dioxide, Sodium
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
Not Applicable
Very fine-grained
Fracture
Conchoidal
Not Available
Porosity
Very Less Porous
Highly Porous
Cleavage
Non-Existent
Slaty
Toughness
Not Available
2.6
Specific Gravity
2.6-2.7
2.2-2.8
Transparency
Translucent
Opaque
Density
2.6 g/cm3
2.4-2.8 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
Bangladesh, China, India, Russia
Africa
Kenya
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
Greece, Hungary, Iceland, Italy, Turkey
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, Mexico, USA
USA
South America
Argentina, Chile, Ecuador, Peru
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand
New South Wales, New Zealand, Queensland, Victoria, Western Australia
All about Obsidian and Shale Properties
Know all about Obsidian and Shale properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian belongs to Igneous Rocks while Shale belongs to Sedimentary Rocks.Texture of Obsidian is Glassy whereas that of Shale is Clastic, Splintery. Obsidian appears Shiny and Shale appears Muddy. The luster of Obsidian is vitreous while that of Shale is dull. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Shale is available in black, brown, buff, green, grey, red, yellow colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Shale are creating artwork, pottery.