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Formula: Mg6Al2(CO3)(OH)16(H2O)4
Hydrated carbonate containing hydroxyl, hydrotalcite group,
hydrotalcite supergroup. The mineral originally named
"manasseite" was considered to be a paramorph of
hydrotalcite, but it has since been renamed as the polytype hydrotalcite-2H, and the
name "manasseite" has been discredited.
Crystal System: Trigonal
Specific gravity: 2.03 to 2.09 measured, 2 calculated
Hardness: 2
Streak: White
Colour: White, brownish
Solubility: Soluble with effervescence in 1:10 hydrochloric acid
Environments
Hydrotalcite occurs as a secondary
mineral in serpentinite, associated with
hydrotalcite-2H, serpentine and
dolomite
(HOM).
Localities
At the type locality, the Dypingdal
serpentine-magnesite
deposit, Snarum, Modum, Viken, Norway, hydrotalcite occurs as contorted, lamellar to fibrous
white masses with waxy or pearly lustre in a
serpentine-magnesite
body associated with steatite and hydrotalcite-2H
(Mindat).
At Bazhenovsk deposit, Asbest, Sverdlovsk Oblast, Russia, asbestos deposit hydrotalcite occurs
with brucite, pyroaurite,
antigorite and calcite
(Dana).
At Antwerp and Oxbow, Jefferson county, New York, USA, hydrotalcite occurs in close association with
hydrotalcite-2H
(Dana).
Amity, Town of Warwick, Orange county, New York, USA, hydrotalcite occurs as an alteration product of
spinel
(Dana).
At Rossie, St. Lawrence county, New York, USA, hydrotalcite occurs in close association with
hydrotalcite-2H
(Dana).
At Somerville, St. Lawrence county, New York, USA, hydrotalcite occurs as an alteration product of
spinel
(Dana).
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