Definition
Rhyolite is a fine-grained igneous rock which is rich in silica
Diabase is a fine-grained igneous rock which is composed mostly of pyroxene and feldspar
Origin
North America
Germany
Discoverer
Ferdinand von Richthofen
Christian Leopold von Buch
Etymology
From German Rhyolit, from Greek rhuax lava stream + lithos stone
From Greek di + base
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, Medium Grained Rock, Opaque Rock
Texture
Aphanitic, Glassy, Porphyritic
Aphanitic, Granular
Color
Grey, White, Light Black
Dark Grey to Black
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Banded
Vesicular
Interior Uses
Decorative Aggregates, Homes, Hotels, Interior Decoration, Kitchens
Countertops, Decorative Aggregates, Homes, Interior Decoration, Kitchens
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
-
Curbing
Construction Industry
Arrowheads, As Dimension Stone, Building houses or walls, Construction Aggregate, Cutting Tool, for Road Aggregate, Knives
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Gemstone, Laboratory bench tops, Jewelry
An Oil and Gas Reservoir, Cemetery Markers, Commemorative Tablets, Laboratory bench tops, Jewelry, Sea Defence, Tombstones
Types
Pumice Rocks, Obsidian Rocks, Perlite Rocks, Porphyritic Rocks.
Dolerite
Features
Acidic in nature, Available in lots of colors
Smooth to touch
Archaeological Significance
Famous Monuments
-
Stonehenge in English county of Wiltshire
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.
Diabase forms when molten igneous rock is squeezed up into a vertical crack in other rocks, the crack is usually forced apart and the molten rock cools in the space to form a tabular igneous intrusion cutting across the surrounding rocks and is known as a dike.
Mineral Content
Biotite, Feldspar, Hornblade, Plagioclase, Pyroxene, Quartz
Augite, Chlorite, Olivine, Plagioclase, Pyroxene, Pyrrhotite, Serpentine
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide, Sodium
Aluminium Oxide, CaO, Chromium(III) Oxide, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Sulfur Trioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Water Erosion
Grain Size
Large and Coarse Grained
Fine to Medium Grained
Fracture
Sub-conchoidal
Conchoidal
Porosity
Highly Porous
Highly Porous
Specific Gravity
2.65-2.67
2.86-2.87
Transparency
Opaque
Opaque
Density
2.4-2.6 g/cm3
2.7-3.3 g/cm3
Resistance
Heat Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
South Africa, Tanzania
Europe
Germany, Iceland, Ireland, Italy, Spain
Germany, Greece, Italy, Scotland, Turkey
Others
-
Antarctica, Greenland
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Argentina, Brazil, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New Zealand, Queensland, Western Australia
Central Australia, New Zealand, Queensland, Western Australia