Antimony

Antimony is a lustrous gray metalloid. While brittle on its own, its most valuable property in technology is its ability to harden other metals, particularly lead.

Description of what it is like

Antimony is a silvery, shiny, and brittle material. Unlike most metals, it is not malleable; hitting it with a hammer will shatter it into crystals. It has a distinctive property of expanding slightly as it cools from a liquid to a solid.

Origin and where to find it

• Environments: Found in hydrothermal veins.
• Signs: Stibnite, the primary ore, often forms long, lead-gray, needle-like crystals.
• It is a natural material that requires smelting.

Minimum processing required

• Liquation: Heating the ore just enough to melt the stibnite and separate it from the rocky gangue.
• Roasting: Converting the sulfide to an oxide.
• Reduction: Heating the oxide with charcoal to produce metallic antimony.

Tools needed to work on it

• Furnaces and crucibles.
• Molds for alloying.
• Mortar and pestle for crushing brittle ore.

Common forms of use

• Type Metal: An alloy of lead, tin, and antimony. The antimony adds hardness and ensures the metal expands to fill every detail of the mold.
• Babbitt Metal: Used for bearings.
• Hardened Lead: For bullets or battery plates.

Possible substitutes

• Arsenic: Also hardens lead but is much more toxic.
• Calcium: Used in some modern lead alloys.
• Tin: Provides some hardening but less than antimony.

Limitations and common failures

• Brittleness: Cannot be used alone for any structural purpose.
• Impurities: Small amounts of arsenic are often present in antimony ores.

Risks and safety

• Toxicity: Antimony and its compounds are toxic. Avoid inhaling dust or fumes.
• Irritation: Can cause skin and eye irritation.

Related materials

• Lead: The primary metal that antimony is used to harden.
• Tin: Often used together with lead and antimony in alloys.
• Charcoal: Used in the reduction process.