Hydrotalcite Mineral Data

Hydrotalcite Mineral Data +

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General Hydrotalcite Information

Chemical Formula:

Mg6Al2(CO3)(OH)16·4(H2O)

Composition:

Molecular Weight = 603.98 gm

Magnesium 24.14 % Mg 40.04 % MgO

Aluminum 8.93 % Al 16.88 % Al₂O₃

Hydrogen 4.01 % H 35.79 % H₂O

Carbon 1.99 % C 7.29 % CO₂

Oxygen 60.93 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg₆Al₂(CO₃)(OH)₁₆·4(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1842

Locality:

Link to MinDat.org Location Data.

Synonym:

ICSD 6296

PDF 41-1428

Hydrotalcite Image

Images:

Hydrotalcite

Comments: Pearly white foliated masses of hydrotalcite on serpentinite rock.
Location: Snarum, Vikersund, Buskerud, Norway. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Hydrotalcite Crystallography

Axial Ratios:

a:c = 1:7.52854

Cell Dimensions:

a = 6.13, c = 46.15, Z = 3; V = 1,501.84 Den(Calc)= 2.00

Crystal System:

Trigonal - Hexagonal ScalenohedralH-M Symbol (3 2/m) Space Group: R 3m

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 7.69(1), 3.88(0.7), 2.58(0.2),

Crystal Structure:

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Allmann R , Jepsen H P , Neues Jahrbuch fur Mineralogie, Monatshefte , 1969 (1969) p.544-551, Die struktur des hydrotalkits, Locality: Vezna, Western Moravia

Physical Properties of Hydrotalcite

Cleavage:

[???] Perfect

Color:

Colorless, White.

Density:

2.06

Diaphaniety:

Transparent

Fracture:

Flexible - Flexible fragments.

Habit:

Foliated - Two dimensional platy forms.

Habit:

Lamellar - Thin laminae producing a lamellar structure.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

2 - Gypsum

Luminescence:

Non-fluorescent.

Luster:

Pearly

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Hydrotalcite

Gladstone-Dale:

CI meas= 0.005 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.024 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2583,KPDmeas= 0.2507,KC= 0.2521

Optical Data:

Uniaxial (-), e=1.495-1.529, w=1.511-1.531, bire=0.0020-0.0160.

Calculated Properties of Hydrotalcite

Electron Density:

r_electron=2.13 gm/cc
note: r_Hydrotalcite=2.06 gm/cc.

Fermion Index

Fermion Index = 0.02466
Boson Index = 0.97534

Photoelectric:

PE_Hydrotalcite= 0.92 barns/electron
U=PE_Hydrotalcite x r_electron= 1.96 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Hydrotalcite is Not Radioactive

Hydrotalcite Classification

Dana Class:

16b.6.2.1 (16b)Carbonates - Hydroxyl or Halogen

(16b.6)Dana Type

(16b.6.2)Sjorgrenite-Hydrotalcite Group (Hydrotalcite Subgroup:Rhombohedral)

16b.6.2.1 Hydrotalcite Mg6Al2(CO3)(OH)16·4(H2O) R 3m 3 2/m

16b.6.2.2 Stichtite Mg6Cr2(CO3)(OH)16·4(H2O) R 3m 3 2/m

16b.6.2.3 Pyroaurite Mg6Fe2(CO3)(OH)16·4(H2O) R 3m 3 2/m

16b.6.2.4 Desautelsite Mg6Mn2(CO3)(OH)16·4(H2O) R 3m or R 3m Trig

Strunz Class:

V/E.03-10 V - Nitrates, Carbonates and Borates

V/E - Water-bearing carbonates with unfamiliar anions

V/E.03 - Hydrotalcite group

V/E.03-10 Hydrotalcite Mg6Al2(CO3)(OH)16·4(H2O) R 3m 3 2/m

V/E.03-20 Stichtite Mg6Cr2(CO3)(OH)16·4(H2O) R 3m 3 2/m

V/E.03-30 Pyroaurite Mg6Fe2(CO3)(OH)16·4(H2O) R 3m 3 2/m

V/E.03-40 Desautelsite Mg6Mn2(CO3)(OH)16·4(H2O) R 3m or R 3m Trig

V/E.03-50 Takovite Ni6Al2(OH)16(CO3,OH)·4(H2O) R 3m 3 2/m

V/E.03-60 Reevesite Ni6Fe2(CO3)(OH)16·4(H2O) R 3m 3 2/m

V/E.03-70 Comblainite Ni6Co2(CO3)(OH)16·4(H2O) R 3m 3 2/m

V/E.03-80 Sergeevite Ca2Mg11(CO3)9(HCO3)4(OH)4·6(H2O) R 32 3 2

Other Hydrotalcite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Hydrotalcite

Mg6Al2(CO3)(OH)16·4(H2O)
Dana No: 16b.6.2.1 Strunz No: V/E.03-10
Locality:

Notes: