Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Larvikite is an igneous rock and a variety of monzonite, notable for the presence of thumbnail-sized crystals of feldspar
Origin
Egypt
Larvik, Norway
Discoverer
Unknown
Unknown
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From the town of Larvik in Norway, where this type of igneous rock is found
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Porphyritic
Phaneritic
Color
Black, Brown, Green, Grey, Red, Rust, White
Black, Brown, Light to Dark Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Construction Aggregate
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments, Sculpture
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Rhomb Porphyry
Quartz Monzonite, Syenite and Diorite
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Available in lots of colors, Is one of the oldest rock
Archaeological Significance
Formation
Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.
Larvikite 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, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Albite, Amphibole, Apatite, Biotite, Feldspar, Hornblade, Ilmenite, Magnetite, Muscovite or Illite, Olivine, Plagioclase, Pyroxene, Quartz, Sulfides, Titanite, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Cataclastic Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion
Grain Size
Fine Grained
Medium to Fine Coarse Grained
Porosity
Less Porous
Less Porous
Luster
Dull
Subvitreous to Dull
Specific Gravity
2.5-4
2.8-3
Transparency
Translucent to Opaque
Opaque
Density
2.5-2.52 g/cm3
2.9-2.91 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Pressure Resistant
Deposits in Eastern Continents
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
-
Africa
Egypt, Ethiopia, Ghana, South Africa
-
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Bulgaria, England, Germany, Norway, Romania, Switzerland
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
New South Wales, New Zealand, Queensland, South Australia, Western Australia