dab tsi yog anhydrite

Anhydrite yog cov ntxhia - anhydrous calcium sulfate, CaS04. Nws yog nyob rau hauv lub orthorhombic crystal system, nrog peb cov lus qhia ntawm zoo meej cleavage parallel mus rau peb lub dav hlau ntawm symmetry. Nws tsis yog isomorphous nrog orthorhombic barium (baryte) thiab strontium (celestine) sulfates, raws li tej zaum yuav xav tau los ntawm cov qauv tshuaj. Distinctly tsim crystals yog me ntsis tsawg, cov ntxhia feem ntau nthuav tawm daim ntawv ntawm cleavage masses. Lub hardness yog 3.5 thiab lub ntiajteb txawj nqus 2.9. Cov xim yog dawb, qee zaum greyish, xiav lossis ntshav. Ntawm qhov zoo tshaj plaws tsim ntawm peb cleavages lub luster yog pearly, nyob rau lwm qhov chaw nws yog vitreous. Thaum raug dej, anhydrite hloov pauv mus rau qhov tshwm sim ntau dua gypsum, (CaS04·2H20) los ntawm kev nqus dej. Qhov kev hloov pauv no yog thim rov qab, nrog gypsum lossis calcium sulfate hemihydrate tsim anhydrite los ntawm cua sov mus rau ~ 200 degree nyob rau hauv ib txwm huab cua. [SJ Anhydrite feem ntau cuam tshuam nrog calcite, halite, thiab sulfides xws li galena, chalcopyrite, molybdenite thiab pyrite hauv cov hlab ntsha. Anhydrite feem ntau pom nyob rau hauv evaporite deposits nrog gypsum; Nws yog, piv txwv li, thawj zaug pom, hauv 1 794, hauv ib lub mine ntsev ze Hall hauv Tirol. Nyob rau hauv qhov tshwm sim qhov tob yog qhov tseem ceeb vim hais tias ze rau qhov chaw anhydrite tau hloov mus rau gypsum los ntawm kev nqus ntawm cov dej hauv av.