Application

Glass and ceramics

Materials made by melting or firing minerals — and one of the largest consumers of industrial minerals by tonnage.

Glass and ceramics are what happens when you heat rock-forming minerals until they change. Glass is cooled fast enough that its atoms never arrange into a crystal; a ceramic is fired until its particles fuse and stays crystalline. The distinction is one of structure rather than of ingredients, and both draw on the same short list of minerals.

That list is where the industrial significance lies. Silica sand, feldspar, clay, limestone, soda ash, borates and talc are consumed in tens of millions of tonnes a year between them, and almost none of it is visible to the people using the results.

Uses

Container and flat glass, tableware, sanitaryware, wall and floor tile, brick, porcelain, insulators, and the technical ceramics used where nothing else survives the temperature or the wear.

Each mineral does a specific job. Silica is the network former and the bulk of the batch. Feldspar supplies alkalis that lower the melting temperature, which is the difference between a furnace that is economic and one that is not — the same function soda ash performs in container glass. Limestone stabilises the resulting glass against water, without which it would slowly dissolve. Clay provides the plasticity that lets a ceramic be shaped before it is fired, and borates give a glass that survives being heated and cooled quickly.

The economics are unusual for an industry this large: the raw materials are cheap and abundant nearly everywhere, so what is actually being bought is the energy to melt them and the freight to move something heavy.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

uses

Quartz — mineral · as silica sand, the network former and the bulk of a glass batch
Feldspar — mineral · one of the largest-tonnage industrial minerals in the world, supplying the alkalis that lower melting temperature
Albite — mineral · the sodium feldspar, and the one preferred where a lower melting temperature matters more than hardness in the fired body
Anorthite — mineral · the calcium end of the plagioclase series, and a constituent of the feldspar concentrates the industry actually buys
Plagioclase — mineral · as feldspar concentrate rather than as a separated species — what is sold is a composition range, not a mineral
Microcline — mineral · the potassium feldspar, favoured in ceramics for the wider firing range it gives
Clay — material · the mineral that makes a ceramic shapeable before it is fired, which is the whole basis of pottery
Borax — mineral · for borosilicate glass, which survives being heated and cooled quickly where soda-lime glass cracks
Talc — mineral · in ceramic bodies, and in the cordierite used for kiln furniture and catalytic converter substrates
Limestone — rock · the stabiliser: without it a soda-silica glass slowly dissolves in water
Soda-lime glass — material · the product itself — ninety per cent of all glass made, in containers and windows
Technical ceramic — material · the demanding end of the same industry, where the material is chosen for what it survives rather than what it looks like
Porcelain — material · the demanding end of the trade, and the reason the industry buys feldspar at all

Sources

Material World
Our own writing

Where it comes from, and what it becomes

Follow Glass and ceramics back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

Glass and ceramics → uses (the demanding end of the same industry, where the material is chosen for what it survives rather than what it looks like) → Technical ceramic → is composed of (alumina is the most-used engineering ceramic) → Aluminium oxide → is sourced from (dissolved out with hot caustic soda in the Bayer process) → Bauxite → is sourced from (the residue of prolonged tropical weathering, which strips the silica and alkalis out of an aluminosilicate rock and leaves the aluminium behind — basalt is one common parent among several) → Basalt → is composed of (an early-crystallising constituent of basaltic magma) → Olivine
Glass and ceramics → uses (the product itself — ninety per cent of all glass made, in containers and windows) → Soda-lime glass → is produced by (drawn off the tin bath as a sheet flat on both surfaces) → Float glass process → takes as input (with difficulty, which is why flat borosilicate costs several times what window glass does) → Borosilicate glass → is produced by (with boron oxide replacing most of the soda, which is what drops the thermal expansion to a third and lets a hot dish go into water) → Glass melting → takes as input (as the stabiliser, and without it a soda-silica glass would slowly dissolve in water) → Limestone
Glass and ceramics → uses (the demanding end of the trade, and the reason the industry buys feldspar at all) → Porcelain → is produced by (at around 1,300 °C — the temperature European potters could not reach, which is half the reason porcelain stayed a Chinese secret for a thousand years) → Firing → takes as input (to 1200–1300 °C, which is the vitrification that separates it from earthenware — and it is a temperature rather than a recipe) → Stoneware → is sourced from (a clay that survives 1200 °C and above, which an earthenware clay does not) → Clay → is sourced from (clay is chiefly what feldspar becomes when it weathers) → Orthoclase
Glass and ceramics → uses (the stabiliser: without it a soda-silica glass slowly dissolves in water) → Limestone → is sourced from (precipitated from it, mostly by organisms building shells and skeletons out of dissolved calcium and carbonate) → Seawater → is composed of (about 96.5 per cent by mass — seawater is 3.5 per cent dissolved solids and the rest of it is this) → Water
Glass and ceramics → uses (the mineral that makes a ceramic shapeable before it is fired, which is the whole basis of pottery) → Clay → is sourced from (clay is chiefly what feldspar becomes when it weathers) → Orthoclase
Glass and ceramics → uses (as silica sand, the network former and the bulk of a glass batch) → Quartz

These are the most distinct paths back. Glass and ceramics can be traced through others besides.