Montroydite is the mineral form of

mercury(II) oxide Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula Hg O. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is ...

with formula HgO. It is a rare mercury mineral. It was first described for an occurrence in the mercury deposit at

Terlingua Terlingua ( ) is a mining district and census-designated place (CDP) in southwestern Brewster County, Texas, Brewster County, Texas, United States. It is located near the Rio Grande and the villages of Lajitas, Texas, Lajitas and Study Bu ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

and named for Montroyd Sharp who was an owner of the deposit. Montroydite occurs in mercury deposits of hydrothermal origin. Associated minerals include: native mercury,

cinnabar Cinnabar (; ), or cinnabarite (), also known as ''mercurblende'' is the bright scarlet to brick-red form of Mercury sulfide, mercury(II) sulfide (HgS). It is the most common source ore for refining mercury (element), elemental mercury and is t ...

, metacinnabar,

calomel Calomel is a Mercury element, mercury chloride mineral with Chemical formula, formula Hg2Cl2 (see mercury(I) chloride). It was used as a medicine from the 16th to early 20th century, despite frequently causing mercury poisoning in patients. The ...

, eglestonite,

terlinguaite Terlinguaite is the naturally occurring mineral with formula . It is formed by the weathering of other mercury (element), mercury-containing minerals. It was discovered in 1900 in the Terlingua, Texas, Terlingua District of Brewster County, Texa ...

, mosesite, kleinite, edgarbaileyite,

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

and dolomite.

References

Mercury(II) minerals Oxide minerals Orthorhombic minerals {{oxide-mineral-stub