Porphyry

Shale

Porphyry and Shale

Porphyry

Shale

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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

Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles

History

Origin

Egypt

Discoverer

Unknown

Johann Gottlob Lehmann

Etymology

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

From German Schalstein laminated limestone, and Schalgebirge layer of stone in stratified rock. From Old English scealu in its base sense of- thing that divides or separate,

Class

Igneous Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Medium Hardness Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Porphyritic

Clastic, Splintery

Color

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

Black, Brown, Buff, Green, Grey, Red, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Muddy

Uses

Architecture

Interior Uses

Decorative Aggregates, Interior Decoration

Decorative Aggregates, Homes, Interior Decoration

Exterior Uses

Garden Decoration, Paving Stone

As Building Stone, As Facing Stone, Office Buildings

Other Architectural Uses

Curbing

Industry

Construction Industry

Construction Aggregate

Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Sculpture

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Creating Artwork, Pottery

Types

Rhomb Porphyry

Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale

Features

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

Easily splits into thin plates, Generally rough to touch, Very fine grained rock

Archaeological Significance

Monuments

Famous Monuments

Jantar Mantar in India

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Present

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.

Shale forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are later compacted hence forming shale.

Composition

Mineral Content

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

Albite, Biotite, Calcite, Chert, Chlorite, Dolomite, Hematite, Micas, Muscovite or Illite, Pyrite, Quartz, Silica, Sulfides

Compound Content

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

Ca, Fe, Mg, Silicon Dioxide, Sodium

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

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

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

6-73

1 7

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Grain Size

Fine Grained

Very fine-grained

Fracture

Irregular

Streak

White

Porosity

Less Porous

Highly Porous

Luster

Dull

Compressive Strength

150.00 N/mm²95.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Toughness

1.7

2.6

Specific Gravity

2.5-42.2-2.8

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.5-2.52 g/cm³2.4-2.8 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.39 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam

Bangladesh, China, India, Russia

Africa

Egypt, Ethiopia, Ghana, South Africa

Ethiopia, Kenya, Morocco, South Africa, Tanzania

Europe

Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland

Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

USA

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

New South Wales, New Zealand, Queensland, Victoria, Western Australia

All about Porphyry and Shale Properties

Know all about Porphyry and Shale properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry belongs to Igneous Rocks while Shale belongs to Sedimentary Rocks.Texture of Porphyry is Porphyritic whereas that of Shale is Clastic, Splintery. Porphyry appears Dull and Shale appears Muddy. The luster of Porphyry and Shale is dull. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Shale is available in black, brown, buff, green, grey, red, yellow colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Shale are creating artwork, pottery.