Image: <bdi><a href="https://www.wikidata.org/wiki/Q126871368" class="extiw" title="d:Q126871368"><span title="photographer from the United States">Darla Sondrol</span></a></bdi> (CC0)
tetragonaluncommonHalides
Calomel
HgCl
Calomel in this sample appears as a yellow, earthy coating or small crystalline aggregates, contrasting with the reddish cinnabar and liquid mercury.
Calomel Physical Properties
Mohs Hardness
1Crystal System
tetragonalLuster
adamantineStreak Color
pale yellowish whiteCleavage
good on {110}Fracture
conchoidal to unevenSpecific Gravity
7.15Colors
white, yellowish, grayish, brownishTransparency
transparent to translucentType Locality
Almadén, Spain; Idrija, Slovenia; Terlingua, Texas, USAMineral Group
HalidesUses
collector, historical medicine, pigmentAssociated Minerals
native mercury, cinnabarRarity
uncommonGeological Context
Calomel is a secondary halide mineral that forms in the oxidized zones of mercury ore deposits, typically as an alteration product of primary mercury minerals like cinnabar or native mercury, often in arid environments.
