Porphyry

Anorthosite

Porphyry and Anorthosite

Porphyry

Anorthosite

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Definition

Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix

Anorthosite is a granular igneous rock composed largely of labradorite or plagioclase

History

Origin

Egypt

Discoverer

Unknown

Etymology

From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites

From French anorthose plagioclase + -ite1

Class

Igneous Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Coarse Grained Rock, Opaque Rock

Texture

Porphyritic

Foliated, Glassy

Color

Black, Brown, Green, Grey, Red, Rust, White

Black, Bluish - Grey, Brown, Green, Grey, Light Greenish Grey, Pink, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Layered, Banded, Veined and Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Floor Tiles, Homes, Interior Decoration

Exterior Uses

Garden Decoration, Paving Stone

As Building Stone, As Facing Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

Construction Aggregate

As Dimension Stone, Cement Manufacture, for Road Aggregate

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Sculpture, Small Figurines

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Creating Artwork, Curling

Types

Rhomb Porphyry

Proterozoic Anorthosite and Archean Anorthosite

Features

Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny

Generally rough to touch, Is one of the oldest rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

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.

Anorthosite is a phaneritic, intrusive igneous rock which is characterized by a predominance of plagioclase feldspar which is almost 90–100%, and a minimal mafic component.

Composition

Mineral Content

Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica

Amphibole, Clinopyroxene, Ilmenite, Magnetite, Olivine, Orthopyroxene

Compound Content

Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide

Ca, CaO, Chromium(III) Oxide, MgO, Sulfur Trioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism

Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Biological Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Wind Erosion

Properties

Physical Properties

Hardness

6-75-6

1 7

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Grain Size

Fine Grained

Coarse Grained

Fracture

Irregular

Streak

White

Porosity

Less Porous

Luster

Dull

Pearly to Subvitreous

Compressive Strength

150.00 N/mm²180.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.7

Specific Gravity

2.5-42.62-2.82

0 8.4

👆🏻

Transparency

Translucent to Opaque

Translucent

Density

2.5-2.52 g/cm³2.7-4 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.84 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant

Reserves

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, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Malta, Poland, Portugal, Romania, Slovenia, Spain, Sweden, The Czech Republic

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

Canada

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Bolivia, Colombia

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

Central Australia, South Australia, Western Australia

All about Porphyry and Anorthosite Properties

Know all about Porphyry and Anorthosite properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry and Anorthosite belong to Igneous Rocks.Texture of Porphyry is Porphyritic whereas that of Anorthosite is Foliated, Glassy. Porphyry appears Dull and Anorthosite appears Layered, Banded, Veined and Shiny. The luster of Porphyry is dull while that of Anorthosite is pearly to subvitreous. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Anorthosite is available in black, bluish - grey, brown, green, grey, light greenish grey, pink, white colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Anorthosite are creating artwork, curling.