←Be   B↑   ↓Al   C→

Bor ∙ bore ∙ boro ∙ boro
group III: R₂O₃

• melting point: 2079°C
• boiling point: 4000°C
• density: 2.34 g/cm³

Borax is used as a flux when welding iron and steel. — wikipedia

⚒ minerals:
Borax (sodium borate) Na₂B₄O₇·5H₂O