Silica Ore & Quartz Sand
title: "Silica Ore & Quartz Sand" description: "SiO₂ raw materials for silicon and silicone production — purity grades, global deposits in Brazil, USA, India, and China, and quality requirements for different end uses." section: "upstream"
What Is Silica Ore?
Silica ore is the primary feedstock for the entire silicon supply chain. In its natural form it appears as quartz rock, quartzite, vein quartz, or silica sand. The key commercial specification is SiO₂ content; everything else — Fe₂O₃, Al₂O₃, TiO₂, CaO — is an impurity.
Quartz sand and quartz lump are the two main traded forms. Lump (quartzite/vein quartz) is charged directly into electric arc furnaces for metallurgical silicon production. Sand is processed into ultra-high-purity granular quartz for semiconductor and photovoltaic applications.
Purity Grades and Applications
| Grade | SiO₂ min (%) | Fe₂O₃ max (%) | Key application |
|---|---|---|---|
| Industrial lump | 97.5 | 0.50 | Metallurgical silicon smelting |
| Chemical-grade sand | 99.5 | 0.02 | Silicates, sodium silicate production |
| High-purity sand | 99.9 | 0.003 | Float glass, optical glass |
| Electronic/solar grade | 99.99 | <0.001 | Semiconductor CZ pulling, solar ingot |
Iron is the most damaging impurity — even trace Fe₂O₃ above 0.3% can degrade downstream silicon quality. High-purity grades require magnetic separation, acid leaching (HF + HCl), flotation, and thermal treatment steps before they meet specification.
Global Supply Geography
Silica is geologically abundant but high-purity deposits suitable for electronics are rare:
- Brazil — Amapá and Minas Gerais host some of the world's largest high-purity quartz reserves; key supplier for European silicon producers.
- USA — Spruce Pine (North Carolina) supplies the highest-purity natural quartz globally; critical for semiconductor crucible and optical fibre manufacture.
- India — Rajasthan and Andhra Pradesh are major exporters of industrial-grade quartz; significant trade flows to China.
- China — Hubei (Huanggang), Shandong, and Inner Mongolia supply domestic metallurgical silicon furnaces; high-purity capacity is growing but still below North American / European quality for semiconductor use.
- Norway — Crystalline quartz deposits feed European ferrosilicon and silicon producers.
Relationship to Downstream Products
Silica ore quality sets a ceiling on what the downstream product can achieve. Metallurgical silicon grade is determined largely by quartz purity and reductant selection. The path from ore to product:
Quartz ore → Metallurgical Silicon → silicone monomers / polysilicon / ferrosilicon
For high-purity applications (semiconductor, solar), quartz purity requirements become extreme — SiO₂ ≥99.9997% for Czochralski-grade crucible silica.