Definition
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Jaspillite is an iron rich chemically formed rock which is common in banded iron formation rocks
Origin
Egypt
Western Australia, Minnesota
Discoverer
Unknown
Unknown
Etymology
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
From Jaspilite (Mineral), a compact siliceous rock which resembles jasper
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Opaque Rock
Texture
Porphyritic
Banded, Trellis
Color
Black, Brown, Green, Grey, Red, Rust, White
Red, Reddish Brown
Durability
Durable
Durable
Appearance
Dull
Banded and Glassy
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
Garden Decoration, Paving Stone
As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Construction Aggregate
As a Flux in the Production of Steel and Pig Iron, As a Sintering Agent in Steel Industry to process Iron Ore, As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Jewellery, Monuments
Commercial Uses
Creating Artwork, Gemstone, Jewelry
Creating Artwork, Jewelry
Types
Rhomb Porphyry
Algoma-type , Lake Superior-type and Superior-type
Features
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
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.
Jaspillite is a type of sedimentary rock which is formed by the compaction and sedimentation of pieces of broken or weathered rocks and minerals.
Mineral Content
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Coesite, Quartz, Sand
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Fe, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
-
Types of Weathering
Biological Weathering, Chemical Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion
Grain Size
Fine Grained
Large and Coarse Grained
Fracture
Irregular
Conchoidal
Porosity
Less Porous
Very Less Porous
Specific Gravity
2.5-4
5.0-5.3
Transparency
Translucent to Opaque
Translucent to Opaque
Density
2.5-2.52 g/cm3
0-5.7 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Russia
Africa
Egypt, Ethiopia, Ghana, South Africa
-
Europe
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Ukraine
Deposits in Western Continents
North America
Canada, Cuba, Jamaica, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Brazil
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Western Australia
Western Australia