Silícea

Silícea, also known as silica, is a widespread mineral composed of silicon and oxygen, with the chemical formula SiO₂. It occurs naturally in crystalline forms such as quartz, as well as in amorphous varieties like opal and diatomaceous earth. In the Earth's crust, silícea constitutes about 59 % of its mass, making it one of the most abundant minerals.

Crystalline silícea appears in a range of polymorphs, including quartz, cristobalite, and tridymite, each distinguished by its crystal structure and stability at different temperatures and pressures. Amorphous silícea lacks a regular lattice and is commonly found in volcanic glass, diatom shells, and certain industrial by‑products.

Silícea has numerous industrial applications. High‑purity quartz is used in glass manufacturing, semiconductors, and optics due to its transparency and thermal stability. Crushed quartz serves as a filler in paints, plastics, and rubber, while diatomaceous earth is employed as a filtration medium and mild abrasive. In construction, silícea sand is a key component of concrete and mortar.

Exposure to respirable crystalline silícea dust can cause silicosis, a progressive lung disease, and has been classified as a carcinogen by several health agencies. Occupational safety regulations typically require dust control measures and personal protective equipment in industries handling fine silícea particles.

Environmental impacts of silícea mining include landscape alteration, habitat disruption, and water quality concerns, prompting the adoption of reclamation practices and monitoring programs in many jurisdictions.