silicon
硅 centers on the element silicon, a hard, brittle crystalline solid used extensively in electronics and as a semiconductor material.
硅 is a modern character created for the chemical element silicon. It combines 石 (stone) with 圭, which likely contributes the sound, reflecting silicon's occurrence in rocks and minerals.
The left side 石 means stone, and silicon is found in many rocks and minerals. The right side 圭 looks like stacked earth, reinforcing the earthy, mineral nature of silicon.
For カク, imagine a silicon chip shaped like a square (四角, しかく) — the カク in しかく cues the reading カク, and the chip is made of silicon.
Lydian stone