Most hemimorphite is found in the rocks above and surrounding zinc deposits. Here, primary zinc ores such as sphalerite were altered to produce hemimorphite as a weathering product, or secondary mineral. Some hemimorphite is also formed where zinc-bearing rocks were subjected to metasomatism.

Hemimorphite can occur as crusts that replaced primary sulfide minerals, crusts of crystals that covered the surfaces of fractures and cavities, or massive to granular aggregates of crystals that fill cavities and replace host rocks. The crystals that produce spectacular mineral specimens are often the last-to-form crystals that grow unobstructed, outward into a subsurface cavity.