Definition
Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth
  
Rhyolite is a fine-grained igneous rock which is rich in silica
  
History
  
  
Origin
Egypt
  
North America
  
Discoverer
Georgius Agricola
  
Ferdinand von Richthofen
  
Etymology
From Late Latin Basaltes (variant of basanites ), very hard stone, which was imported from Ancient Greek Basanites
  
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
  
Family
  
  
Group
Volcanic
  
Volcanic
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Coarse Grained Rock, Opaque Rock
  
Texture
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
  
Aphanitic, Glassy, Porphyritic
  
Color
Black, Brown, Light to Dark Grey
  
Grey, White, Light Black
  
Maintenance
More
  
More
  
Durability
Durable
  
Durable
  
Water Resistant
No
  
Yes
  
Scratch Resistant
Yes
  
Yes
  
Stain Resistant
Yes
  
Yes
  
Wind Resistant
No
  
Yes
  
Acid Resistant
Yes
  
Yes
  
Appearance
Dull and Soft
  
Banded
  
Architecture
  
  
Interior Uses
Floor Tiles, Homes, Hotels, Kitchens
  
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
  
Exterior Uses
As Building Stone, Paving Stone, Garden Decoration, Office Buildings
  
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
  
Other Architectural Uses
Curbing, Whetstones
  
Not Yet Used
  
Industry
  
  
Construction Industry
Arrowheads, As Dimension Stone, Cobblestones, Cutting Tool, Rail Track Ballast, Roadstone
  
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts, Monuments
  
Artifacts
  
Other Uses
  
  
Commercial Uses
An Oil and Gas Reservoir, Commemorative Tablets, Creating Artwork, Used in aquariums
  
Gemstone, Laboratory bench tops, Jewelry
  
Types
Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite
  
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
  
Features
Has High structural resistance against erosion and climate, Very fine grained rock
  
Acidic in nature, Available in lots of colors
  
Archaeological Significance
  
  
Monuments
Used
  
Not Yet Used
  
Famous Monuments
Easter Island in the Polynesian Triangle, Pacific Ocean, Gateway of India in Mumbai, India, Gol Gumbaz in Karnataka, India
  
Not Applicable
  
Sculpture
Used
  
Not Yet Used
  
Famous Sculptures
Data Not Available
  
Not Applicable
  
Pictographs
Used
  
Not Used
  
Petroglyphs
Used
  
Not Used
  
Figurines
Used
  
Not Yet Used
  
Fossils
Absent
  
Absent
  
Formation
Basalt forms when lava reaches the Earth's surface near an active volcano. The temperature of lava is between 1100 to 1250° C when it gets to the surface.
  
Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.
  
Composition
  
  
Mineral Content
Olivine, Plagioclase, Pyroxene
  
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
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Contact Metamorphism
  
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
No
  
Yes
  
Types of Erosion
Not Available
  
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
6
  
6-7
  
Grain Size
Fine Grained
  
Large and Coarse Grained
  
Fracture
Conchoidal
  
Sub-conchoidal
  
Streak
White to Grey
  
Colorless
  
Porosity
Less Porous
  
Highly Porous
  
Luster
Not Available
  
Earthy
  
Compressive Strength
37.40 N/mm2
  
28
140.00 N/mm2
  
15
Cleavage
Not Available
  
Not Available
  
Toughness
2.3
  
2
  
Specific Gravity
2.8-3
  
2.65-2.67
  
Transparency
Opaque
  
Opaque
  
Density
2.9-3.1 g/cm3
  
2.4-2.6 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
0.84 kJ/Kg K
  
15
Not Available
  
Resistance
Heat Resistant, Pressure Resistant, Wear Resistant
  
Heat Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
India, Russia
  
China, India
  
Africa
South Africa
  
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
  
Europe
Iceland
  
Germany, Iceland, Ireland, Italy, Spain
  
Others
Not Yet Found
  
Not Yet Found
  
Deposits in Western Continents
  
  
North America
Canada, USA
  
Canada, USA
  
South America
Brazil
  
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
  
Deposits in Oceania Continent
  
  
Australia
Not Yet Found
  
New Zealand, Queensland, Western Australia