Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine
Origin
North America
Hawaii Islands
Discoverer
Ferdinand von Richthofen
Unknown
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Greek pikros bitter + -ite, 19th century
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic, Glassy, Porphyritic
Earthy, Rough
Color
Grey, White, Light Black
Black, Brown, Green, Grey, Pink, White, Yellow
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Banded
Rough and Shiny
Interior Uses
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Countertops, Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
As a Sintering Agent in Steel Industry to process Iron Ore, Cement Manufacture, for Road Aggregate, Manufacture of Magnesium and Dolomite Refractories, Roadstone, Used for flooring, stair treads, borders and window sills.
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture
Commercial Uses
Gemstone, Laboratory bench tops, Jewelry
As a Feed Additive for Livestock, As armour rock for sea walls, Metallurgical Flux, Pottery, Source of Magnesia (MgO)
Types
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Oceanite
Features
Acidic in nature, Available in lots of colors
Host Rock for Lead
Archaeological Significance
Formation
Rhyolite is a felsic extrusive rock and due to its high silica content, rhyolite lava is very viscous and is volcanic equivalent of granite.
Picrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Mineral Content
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Biotite, Olivine, Plagioclase, Pyrrhotite
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
Al, CaO, Carbon Dioxide, Mg, MgO
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Large and Coarse Grained
Fine Grained
Fracture
Sub-conchoidal
Uneven
Streak
-
White, Greenish White or Grey
Porosity
Highly Porous
Less Porous
Luster
Earthy
Subvitreous to Dull
Specific Gravity
2.65-2.67
2.75-2.92
Transparency
Opaque
Opaque
Density
2.4-2.6 g/cm3
1.5-2.5 g/cm3
Resistance
Heat Resistant, Wear Resistant
Heat Resistant
Deposits in Eastern Continents
Asia
China, India
India, Russia
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
South Africa
Europe
Germany, Iceland, Ireland, Italy, Spain
Iceland
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Brazil
Deposits in Oceania Continent
Australia
New Zealand, Queensland, Western Australia
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All about Rhyolite and Picrite Properties
Know all about Rhyolite and Picrite properties here. All properties of rocks are important as they define the type of rock and its application. Rhyolite and Picrite belong to Igneous Rocks.Texture of Rhyolite is Aphanitic, Glassy, Porphyritic whereas that of Picrite is Earthy, Rough. Rhyolite appears Banded and Picrite appears Rough and Shiny. The luster of Rhyolite is earthy while that of Picrite is subvitreous to dull. Rhyolite is available in grey, white, light black colors whereas Picrite is available in black, brown, green, grey, pink, white, yellow colors. The commercial uses of Rhyolite are gemstone, laboratory bench tops, jewelry and that of Picrite are as a feed additive for livestock, as armour rock for sea walls, metallurgical flux, pottery, source of magnesia (mgo).