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
Rhyolite is a fine-grained igneous rock which is rich in silica
Origin
Ethiopia
North America
Discoverer
Obsius
Ferdinand von Richthofen
Etymology
From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius
From German Rhyolit, from Greek rhuax lava stream + lithos stone
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Other Categories
Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Glassy
Aphanitic, Glassy, Porphyritic
Color
Black, Blue, Brown, Green, Orange, Red, Tan, Yellow
Grey, White, Light Black
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Exterior Uses
Garden Decoration
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
Other Architectural Uses
-
-
Construction Industry
Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
Medical Industry
Surgery
-
Antiquity Uses
Artifacts, Jewellery
Artifacts
Commercial Uses
Creating Artwork, Mirror, Used in aquariums
Gemstone, Laboratory bench tops, Jewelry
Types
Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Features
Blocks negativity, Helps to protect against depression
Acidic in nature, Available in lots of colors
Archaeological Significance
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.
Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.
Mineral Content
-
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
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, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
-
Large and Coarse Grained
Fracture
Conchoidal
Sub-conchoidal
Porosity
Very Less Porous
Highly Porous
Specific Gravity
2.6-2.7
2.65-2.67
Transparency
Translucent
Opaque
Density
2.6 g/cm3
2.4-2.6 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Afghanistan, Indonesia, Japan, Russia
China, India
Africa
Kenya
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Europe
Greece, Hungary, Iceland, Italy, Turkey
Germany, Iceland, Ireland, Italy, Spain
Deposits in Western Continents
North America
Canada, Mexico, USA
Canada, USA
South America
Argentina, Chile, Ecuador, Peru
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand
New Zealand, Queensland, Western Australia
All about Obsidian and Rhyolite Properties
Know all about Obsidian and Rhyolite properties here. All properties of rocks are important as they define the type of rock and its application. Obsidian and Rhyolite belong to Igneous Rocks.Texture of Obsidian is Glassy whereas that of Rhyolite is Aphanitic, Glassy, Porphyritic. Obsidian appears Shiny and Rhyolite appears Banded. The luster of Obsidian is vitreous while that of Rhyolite is earthy. Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors whereas Rhyolite is available in grey, white, light black colors. The commercial uses of Obsidian are creating artwork, mirror, used in aquariums and that of Rhyolite are gemstone, laboratory bench tops, jewelry.