Quartz (likely a clear or rock crystal variety)

Hardness: 7 (Mohs scale), Color: Clear/colorless (as seen in image), Luster: Vitreous (glassy), Crystal structure: Hexagonal (often forms hexagonal prisms with pyramidal terminations), Cleavage: None, Specific Gravity: 2.65

Quartz forms in a wide range of geological environments, including igneous, metamorphic, and sedimentary rocks. It crystallizes from silica-rich magmas or hydrothermal veins at various temperatures and pressures. Its geological age varies widely depending on the specific deposit, ranging from billions of years old to relatively recent formations.

Industry: Used in electronics (oscillators, filters), optics (lenses, prisms), abrasives, and glass manufacturing. Jewelry: Many varieties (e.g., amethyst, citrine, smoky quartz, rose quartz, clear quartz/rock crystal) are highly valued as gemstones. Construction: Found in sand and gravel, crucial for concrete and mortar. Collecting: Highly prized by mineral collectors for its crystal forms and variety of colors.

Quartz is the second most abundant mineral in Earth's continental crust, after feldspar. It exhibits piezoelectric properties, meaning it can generate an electrical charge when mechanically stressed, and vice versa. This property makes it invaluable in electronics. Amethyst, citrine, rose quartz, and smoky quartz are all varieties of quartz.

Identify in the field: Look for its hardness (scratches glass), vitreous luster, and often characteristic hexagonal crystal habit. It does not cleave, but can fracture conchoidally (shell-like). Commonly found: Ubiquitous in continental crust; significant deposits in Brazil, Arkansas (USA), the Alps, and various other locations worldwide. Tips for collectors: Seek out well-formed crystals, particularly those with good clarity and interesting inclusions. Varieties with vibrant colors are also highly sought after.