Heliodor (Yellow Beryl) / Greenish-Yellow Beryl

Hardness: 7.5-8 on Mohs scale. Color: Yellowish-green to golden yellow. Luster: Vitreous. Crystal system: Hexagonal (prismatic crystal habit with vertical striations). Specific gravity: 2.63-2.90.

Formed primarily in granitic pegmatites and pneumatolytic hydrothermal veins during the late stages of magmatic crystallization where beryllium becomes concentrated.

Used widely as a gemstone in fine jewelry (faceted or carved) and prized as a collector specimen in crystal form.

The name Heliodor comes from the Greek words 'helios' (sun) and 'doron' (gift), meaning 'gift from the sun'. Its distinct yellow coloration is caused by trace amounts of iron (Fe3+) within the crystal lattice.

Identified by its hexagonal prism shape, distinct striations along the length of the crystal faces, and high hardness (scratches glass/quartz). Note: Beryl minerals are not native to the immediate surface bedrock of Central Illinois (approx. 39.8°N, 89.7°W), so if found locally, it represents an imported gem/specimen or potentially a glacial erratic transport.