Conglomerate

A conglomerate is a type of sedimentary rock formed from rounded rock fragments or pebbles that are cemented together by a finer-grained matrix, such as sand or silt.

The rock fragments can be composed of different minerals and rocks – the easiest way to imagine a conglomerate is to imagine a man-made conglomerate: a block of cement with old bricks, glass, and other mill waste mixed in.

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Information about Conglomerate

Conglomerate is a clastic sedimentary rock composed of rounded clasts (pebbles, cobbles, or boulders) that are greater than 2 mm in diameter, cemented together by finer-grained matrix material such as sand, silt, or clay.

The clasts are typically well-rounded, indicating significant transport by water or glacial action, and may consist of a variety of rock or mineral types. Colours vary widely depending on the composition, ranging from brown and grey to reddish or greenish tones.

Conglomerate may be known by other names locally, including puddingstone in the UK.

 

Uses and History

Though not commonly used as a construction material due to its heterogeneous nature and variability, conglomerate may be employed in decorative stonework, landscaping, and occasionally as dimension stone.

The study of conglomerate dates back to the early development of sedimentary geology. Its rounded clasts sparked early theories about transport mechanisms and depositional environments. Famous examples include the Puddingstone of Hertfordshire (UK) and the Jacobsville Conglomerate in Michigan, USA.

 

Mineralogy

Chemistry
No fixed formula – a mixture of rocks.
Colours and Variations

Commonly brown, grey, red, black. Varies based on composition.

Streak
Various.
Luster
Dull to earthy
Transparency
Opaque.
Fracture
Opaque.
Crystal habit
N/A
Mohs hardness
Various.
Fluorescence
Various.
Specific Gravity
Various.
Easiest testing method
Visual ID.

Hazards and Warnings

Mineral collectors should wash their hands after handling specimens, to avoid any exposure to potential toxins.

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.

When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

 

Translations

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English:

  • Conglomerate

Italian:

  • Conglomerato

Russian:

  • Конгломерат

French:

  • Conglomérat

Japanese:

  • 礫岩

Spanish:

  • Konglomerat

German:

  • Konglomerat

Korean:

  • 역암

Thai:

Gujurati:

Mandarin Chinese:

  • 砾岩

Urdu:

Further Reading / External Links