Milky quartz

White to translucent, vitreous-to-waxy luster; typically hardness 7 Mohs, no cleavage, and conchoidal fracture. The blocky appearance may reflect a natural fracture or a cut/tumbled piece; crystal structure is trigonal, though faces are not obvious here.

Forms when silica-rich fluids fill cavities and fractures in igneous, metamorphic, or sedimentary rocks. Quartz is geologically widespread and ranges from ancient to modern; this specimen’s age cannot be determined from the photograph.

Common quartz is used in glass, ceramics, abrasives, electronics, and engineered stone. Attractive translucent pieces are collected, though this small specimen has modest value.

The cloudy appearance results from microscopic fluid inclusions, fractures, or mineral impurities. It may also be a small piece of crystalline quartz rather than a complete crystal.

Likely identification based on its translucent white color and glassy appearance. Test cautiously: quartz scratches ordinary glass, while a steel knife generally does not scratch it; inspect for bubbles, which would suggest glass. Quartz is common around Budapest and the surrounding Transdanubian region, so the reported location is plausible.