Industrial minerals

Untreated Rock Products

Building stone

Cut (dimension) stone

Ashlar

Monumental stone

Flagstone

Roofing Slate

Terrazzo

Some commonly used rocks

Granite (includes “black granite”=gabbro, larvikite

Sandstone

Limestone

Marble (recrystallized and metamorphosed limestones)

Serpentinite

Slate

Crushed rock

Used for construction, aggregate

Hard, inert not reactive with cement – maninly limestone, granite, traprock(volcanic lavas), sandstone

Sand and Gravel

Aggregate. Alluvial fans, glacial deposts, occasionally beaches. Some submarine deposits

Treated rock products

Cement

Mortar – mixed with sand to produce binding agent for masonry

Concrete – mixed with sand and gravel – a kind of artificial rock.

Original made by Romans by calcining limestone (CaCO₃) to make lime(CaO), mixed with volcanic ash and water

Modern cement – Portland Cement - Limestone and clay ground together and then heated to 1500⁰C to produce clinker. Clinker then crushed and mixed with some gypsum (CaSO₄. 2H₂O)

Plaster

Calcining gypsum – water driven off to form plaster of Paris (CaSO₄. 0.5H₂O). Mixed with water for use, rehydrates to gypsum. Glue and starch can be added to reduce setting time.

Gypsum widely distributed in US – largest producer and consumer.

Brick and ceramics

Produced from clays (silicates). Plastic when wet so can be moulded. When fired, water given off and mixture partially melts and fuses

China clay (kaolinite) - fine porcelain also filler for paper

Ball clay (mainly kaolinite) –electrical insulators

Glass

Made from silica sand mixed with Soda (Na2O from sodium carbonate or sodium nitrate or rock salt) to reduce melting temperature. Calcium (limestone) and alumina (Al₂O₃)added to improve chemical stability.

Other industrial minerals

Asbestos

Group of minerals that form fibrous masses: Chrysotile, crocidolite, amosite, anthophyllite, tremolite, actinolite. Can be spun, woven or embedded in other materials. Heat resistant, electrical insulators and high tensile strength

Brake linings, clutch plates, cement products

Found in altered ultramafic rocks – opiolite complexes

Safe when firmly encapsulated in matrix material. Dangerous when in air. Latter can occur when materials get old and break down.

Abrasives

Diamond, garnet, corundum

Gemstones