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Material World
Mineral · Mg2SiO4

Forsterite

The magnesium end of the olivine series — a refractory mineral that makes furnace linings and, in gem quality, peridot.

Refractory

Forsterite is magnesium olivine, the end of the series with no iron in it, and its properties are what make olivine industrially useful. It melts near 1890 degrees where the iron end melts some 700 degrees lower, so the value of an olivine deposit depends heavily on how magnesium-rich it is.

It is also the dominant mineral of the Earth's upper mantle, which makes it, by mass, one of the most abundant minerals in the planet — most of it several tens of kilometres beneath anywhere anyone has stood.

How it forms

Forsterite crystallises early and hot from magnesium-rich magma and accumulates at the base of magma chambers as dunite. It also forms during the metamorphism of impure dolomitic limestone, where magnesium carbonate and silica react as the rock is heated.

At the surface it weathers quickly. Water converts it to serpentine, releasing magnesium — a reaction favourable enough to be pursued deliberately as a carbon capture route, because the magnesium set free will bind carbon dioxide as solid carbonate.

Uses

Foundry sand and refractory brick take most of it. Forsterite resists attack by molten iron and slag and does not fuse at steelmaking temperatures, which is why olivine sand is used for casting moulds and olivine brick lines furnaces.

It is also used as a slag conditioner in blast furnaces and, increasingly, as feedstock for enhanced weathering — crushing and spreading it to accelerate the carbon dioxide reaction that would otherwise take geological time. Gem-quality forsterite is peridot.

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.

belongs to the group

  • Olivine — mineral · the magnesium end member Wikidata

contains

is used as

  • Refractory lining — application · olivine brick and foundry sand, which resist molten iron and slag

is a component of

  • Kimberlite — rock · the magnesian end of the olivine series, which is what mantle olivine is — the same crystals as the group edge above, named more precisely
  • Peridotite — rock · the magnesian end of the olivine series, and what mantle olivine actually is — around ninety per cent forsterite in most peridotite
  • Refractory brick — material · the magnesium end of olivine, used as a basic refractory where magnesite is not to hand

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)

Questions this page answers

Where it comes from, and what it becomes

Follow Forsterite 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.

Downstream — what it becomes

  • Forsterite → is a component of (the magnesian end of the olivine series, and what mantle olivine actually is — around ninety per cent forsterite in most peridotite) → Peridotite → is a source for (partial melting of mantle peridotite is what basalt magma is — the residue left behind stays peridotite, depleted of what went into the melt) → Basalt → is an input to (for aggregate rather than dimension stone — hard, tough and angular, which is what a road base needs) → Quarrying → produces (cut rather than blasted, because a quarry that shatters its stone has destroyed what it came for) → Dimension stone → is used in (cladding, flooring, kerbs and monuments) → Construction
  • Forsterite → is a component of (the magnesium end of olivine, used as a basic refractory where magnesite is not to hand) → Refractory brick → is an input to (or installed unfired as a monolithic castable and cured by the furnace's own first heat) → Firing → produces (as sintering, from refined powders rather than clay) → Technical ceramic → is used in (the honeycomb monolith the metals are dispersed across, which supplies the surface area and survives the thermal cycling) → Catalytic converter → is used as (the largest catalytic application by metal value there is) → Catalysis
  • Forsterite → is used as (olivine brick and foundry sand, which resist molten iron and slag) → Refractory lining
  • Forsterite → is a component of (the magnesian end of the olivine series, which is what mantle olivine is — the same crystals as the group edge above, named more precisely) → Kimberlite
  • Forsterite → is a component of (the magnesian end of the olivine series, and what mantle olivine actually is — around ninety per cent forsterite in most peridotite) → Peridotite → is a source for (serpentinite is hydrated peridotite; the protolith is the mantle rock itself) → Serpentinite → is a source for (chrysotile is serpentine that crystallised across an opening crack, which is why it occurs as cross-fibre veins and why serpentinite hosts most of what was ever mined) → Asbestos
  • Forsterite → is a component of (the magnesium end of olivine, used as a basic refractory where magnesite is not to hand) → Refractory brick → is an input to (or installed unfired as a monolithic castable and cured by the furnace's own first heat) → Firing → produces (fired in a continuous tunnel kiln, the atmosphere governing colour as much as the temperature) → Brick → is used in (load-bearing walls and cladding) → Construction

These are the most distinct paths onward. Forsterite ends up in others besides.