Porphyry

Chalk

Porphyry and Chalk

Porphyry

Chalk

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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

Chalk is a soft, white, powdery limestone consisting mainly of fossil shells of foraminifers

History

Origin

Egypt

Discoverer

Unknown

Etymology

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

From old English cealc chalk, lime, plaster; pebble, from Greek khalix small pebble, in English transferred to the opaque, white, soft limestone

Class

Igneous Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Hard Rock

Durable Rock, Soft Rock

Family

Group

Plutonic

Other Categories

Fine Grained Rock, Opaque Rock

Texture

Porphyritic

Clastic or Non-Clastic

Color

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

Grey, White, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Dull

Soft

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, Paving Stone, Garden Decoration

Other Architectural Uses

Curbing

Powder

Industry

Construction Industry

Construction Aggregate

As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, raw material for manufacture of quicklime and slaked lime, Source of calcium

Medical Industry

Antiquity Uses

Artifacts, Monuments, Sculpture

Artifacts, Monuments, Sculpture, Small Figurines

Other Uses

Commercial Uses

Creating Artwork, Gemstone, Jewelry

Alumina Refineries, Creating Artwork, Drawing on blackboards, Gymnasts, athletes and mountain climbers use for grip, In aquifers, Paper Industry, Production of Lime, Raw material for manufacture of quicklime, slaked lime, Soil Conditioner, Whiting, Whiting material in toothpaste, paint and paper

Types

Rhomb Porphyry

Chalk Marl and Marl

Features

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

Clasts are smooth to touch, Is one of the oldest rock, Smooth to touch, Very fine grained rock

Archaeological Significance

Monuments

Famous Monuments

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.

Chalk is formed from lime mud, which accumulates on the sea floor which is then transformed into rock by geological processes.

Composition

Mineral Content

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

Calcite, Clay, Clay Minerals, Quartz, Sand

Compound Content

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

Ca, NaCl, CaO

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

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion, Coastal Erosion, Water Erosion

Properties

Physical Properties

Hardness

6-71

1 7

👆🏻

Grain Size

Fine Grained

Very fine-grained

Fracture

Irregular

Streak

White

Porosity

Less Porous

Highly Porous

Luster

Dull

Compressive Strength

150.00 N/mm²5.00 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

1.7

Specific Gravity

2.5-42.3-2.4

0 8.4

👆🏻

Transparency

Translucent to Opaque

Opaque

Density

2.5-2.52 g/cm³2.49-2.50 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.71 kJ/Kg K0.90 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant

Heat Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Brunei, India, Indonesia, Malaysia, Singapore, Thailand, Vietnam

Africa

Egypt, Ethiopia, Ghana, South Africa

Cameroon, Chad, Ghana, Kenya, Malawi, Sudan, Tanzania, Togo, Zambia, Zimbabwe

Europe

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

England, France, Germany, Spain, United Kingdom

Others

Greenland

Deposits in Western Continents

North America

Canada, Cuba, Jamaica, USA

Canada, USA

South America

Bolivia, Brazil, Colombia, Ecuador, Paraguay

Colombia

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Western Australia

Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula

All about Porphyry and Chalk Properties

Know all about Porphyry and Chalk properties here. All properties of rocks are important as they define the type of rock and its application. Porphyry belongs to Igneous Rocks while Chalk belongs to Sedimentary Rocks.Texture of Porphyry is Porphyritic whereas that of Chalk is Clastic or Non-Clastic. Porphyry appears Dull and Chalk appears Soft. The luster of Porphyry and Chalk is dull. Porphyry is available in black, brown, green, grey, red, rust, white colors whereas Chalk is available in grey, white, yellow colors. The commercial uses of Porphyry are creating artwork, gemstone, jewelry and that of Chalk are alumina refineries, creating artwork, drawing on blackboards, gymnasts, athletes and mountain climbers use for grip, in aquifers, paper industry, production of lime, raw material for manufacture of quicklime, slaked lime, soil conditioner, whiting, whiting material in toothpaste, paint and paper.