Quick Facts
Formation & Origin
Legrandite forms as a secondary mineral in the oxidation zone of zinc-arsenic ore deposits, where zinc-rich and arsenic-rich solutions combine under acidic conditions. The crystals precipitate in open cavities within limonite and iron oxide matrix.
The Ojuela Mine in Mapimí, Mexico produces the world's most spectacular legrandite specimens. There, vivid yellow prismatic crystals grow in sprays and clusters within iron-stained limestone cavities. The best specimens feature elongated crystals up to 10cm long with intense, saturated color and brilliant vitreous luster.
Legrandite's intense yellow color comes from the zinc-arsenate chemistry itself rather than from trace elements. This means the vivid color is inherent to the mineral rather than variable, making every well-crystallized legrandite specimen naturally vivid.
Identification Guide
Legrandite is identified by its intense lemon-yellow color, elongated prismatic crystal habit, and association with zinc-arsenic ore deposits. The vitreous luster on crystal faces is particularly bright. Specific gravity of 4.01 makes it noticeably heavier than its appearance suggests.
Distinguish from adamite (can be yellow but more commonly green, different crystal habit), sulfur (softer, melts easily, lower SG), and yellow calcite (softer, effervesces in acid). Legrandite's combination of vivid yellow, high SG, and prismatic habit is distinctive. SAFETY: Contains arsenic. Handle carefully.
Spotting Fakes
Legrandite is not commonly faked because it's a niche collector mineral. The main concern is quality and provenance. Ojuela Mine specimens with large, well-formed crystals are the most valuable. Some specimens may have crystals repaired or reattached, so check crystal attachment points under magnification for glue residue.
Cultural & Metaphysical Traditions
Presented as cultural traditions, not scientific evidence
Legrandite is associated with joy, optimism, and personal sunshine in crystal healing. Its bright yellow color connects it strongly to solar plexus energy and themes of confidence and warmth. Practitioners use it for lifting spirits and attracting positivity. IMPORTANT: Contains arsenic. Display only. Handle with care and wash hands after.
Where It's Found
World's finest specimens, stunning crystal sprays
Fine crystallized specimens
Minor occurrences
Type locality, originally described from here
Price Guide
Good to Know
Scratch test: At hardness 4.5, Legrandite can be scratched with a copper coin. Handle gently and keep away from harder stones in your collection.
Sources: Found in 4 notable locations worldwide, from Mexico to Germany.
Heft test: Legrandite has a specific gravity of 4.01 - noticeably heavier than quartz. You'll feel the density when you pick it up.
Related Minerals
Another zinc arsenate from similar deposits
Zinc arsenate polymorph
Another vivid yellow mineral from oxidation zones