Chalk

Obsidian

Chalk and Obsidian

Chalk

Obsidian

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Definition

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

Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools rapidly with minimum crystal growth

History

Origin

Ethiopia

Discoverer

Unknown

Obsius

Etymology

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

From Latin obsidianus, misprint of Obsianus (lapis) (stone) of Obsius

Class

Sedimentary Rocks

Igneous Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Medium Hardness Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Opaque Rock

Opaque Rock

Texture

Clastic or Non-Clastic

Glassy

Color

Grey, White, Yellow

Black, Blue, Brown, Green, Orange, Red, Tan, Yellow

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Soft

Shiny

Uses

Architecture

Interior Uses

Decorative Aggregates, Homes, Interior Decoration

Decorative Aggregates, Interior Decoration

Exterior Uses

As Building Stone, As Facing Stone, Paving Stone, Garden Decoration

Garden Decoration

Other Architectural Uses

Powder

Industry

Construction Industry

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

Arrowheads, Cutting Tool, Knives, Scrapers, Spear Points

Medical Industry

Surgery

Antiquity Uses

Artifacts, Monuments, Sculpture, Small Figurines

Artifacts, Jewellery

Other Uses

Commercial Uses

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

Creating Artwork, Mirror, Used in aquariums

Types

Chalk Marl and Marl

Fireworks Obsidian, Mahogany, Sheen Obsidian, Snowflake obsidian and Velvet Peacock Obsidian

Features

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

Blocks negativity, Helps to protect against depression

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Present

Absent

Formation

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

When the lava is released from volcano, it undergoes a very rapid cooling which freezes the mechanisms of crystallization. The result is a volcanic glass with a uniform smooth texture.

Composition

Mineral Content

Calcite, Clay, Clay Minerals, Quartz, Sand

Compound Content

Ca, NaCl, CaO

Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Water Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Properties

Physical Properties

Hardness

15-5.5

1 7

👆🏻

Grain Size

Very fine-grained

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Very Less Porous

Luster

Dull

Vitreous

Compressive Strength

5.00 N/mm²0.15 N/mm²

0.15 450

👆🏻

Cleavage

Toughness

Specific Gravity

2.3-2.42.6-2.7

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

2.49-2.50 g/cm³2.6 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.90 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant

Heat Resistant, Impact Resistant

Reserves

Deposits in Eastern Continents

Asia

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

Afghanistan, Indonesia, Japan, Russia

Africa

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

Kenya

Europe

England, France, Germany, Spain, United Kingdom

Greece, Hungary, Iceland, Italy, Turkey

Others

Deposits in Western Continents

North America

Canada, USA

Canada, Mexico, USA

South America

Colombia

Argentina, Chile, Ecuador, Peru

Deposits in Oceania Continent

Australia

Adelaide, New Zealand, Queensland, Victoria, Yorke Peninsula

New Zealand

All about Chalk and Obsidian Properties

Know all about Chalk and Obsidian properties here. All properties of rocks are important as they define the type of rock and its application. Chalk belongs to Sedimentary Rocks while Obsidian belongs to Igneous Rocks.Texture of Chalk is Clastic or Non-Clastic whereas that of Obsidian is Glassy. Chalk appears Soft and Obsidian appears Shiny. The luster of Chalk is dull while that of Obsidian is vitreous. Chalk is available in grey, white, yellow colors whereas Obsidian is available in black, blue, brown, green, orange, red, tan, yellow colors. The commercial uses 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 and that of Obsidian are creating artwork, mirror, used in aquariums.