Hydrotalcite Mineral Data

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)

Environment:

Secondary mineral in serpentinite. Dimorphous with manasseite.

IMA Status:

Valid Species (Pre-IMA) 1842

Locality:

Snarum, Norway. Link to MinDat.org Location Data.

Name Origin:

Named as a HYDROus mineral with a resemblance to talc.

Name Pronunciation:

Hydrotalcite + Pronunciation

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

Diaphaneity:

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
Ncalc = 1.5 - 1.52

Optical Data:

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

Calculated Properties of Hydrotalcite

Electron Density:

Bulk Density (Electron Density)=2.13 gm/cc
note: Specific Gravity of Hydrotalcite =2.06 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Hydrotalcite= 0.92 barns/electron
U=PE_Hydrotalcite x rElectron Density= 1.96 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Hydrotalcite is Not Radioactive

Hydrotalcite Classification

Dana Class:

16b.06.02.01 (16b)Carbonates - Hydroxyl or Halogen

(16b.06)Dana Type

(16b.06.02)Sjorgrenite-Hydrotalcite Group (Hydrotalcite Subgroup:Rhombohedral)

16b.06.02.01 Hydrotalcite Mg6Al2(CO3)(OH)16•4(H2O) R 3m 3 2/m

16b.06.02.02 Stichtite Mg6Cr2(CO3)(OH)16•4(H2O) R 3m 3 2/m

16b.06.02.03 Pyroaurite Mg6Fe2(CO3)(OH)16•4(H2O) R 3m 3 2/m

16b.06.02.04 Desautelsite Mg6Mn2(CO3)(OH)16•4(H2O) R 3m or R 3m Trig

16b.06.02.05 Droninoite! Ni3FeCl(OH)8•2H2O R 3m, R 3m or R 32 Trig

Strunz Class:

05.DA.50 05 - CARBONATES (NITRATES)

05.D - Carbonates with Additional Anions, with H2O

05.DA -With medium-sized cations

05.DA.50 Desautelsite Mg6Mn2(CO3)(OH)16•4(H2O) R 3m or R 3m Trig

05.DA.50 Comblainite Ni6Co2(CO3)(OH)16•4(H2O) R 3m 3 2/m

05.DA.50 Hydrotalcite Mg6Al2(CO3)(OH)16•4(H2O) R 3m 3 2/m

05.DA.50 Pyroaurite Mg6Fe2(CO3)(OH)16•4(H2O) R 3m 3 2/m

05.DA.50 Reevesite Ni6Fe2(CO3)(OH)16•4(H2O) R 3m 3 2/m

05.DA.50 Stichtite Mg6Cr2(CO3)(OH)16•4(H2O) R 3m 3 2/m

05.DA.50 Takovite Ni6Al2(OH)16(CO3,OH)•4(H2O) R 3m 3 2/m

Other Hydrotalcite Information

References:

NAME( AntBidBlaNic3) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Hydrotalcite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Franklin Minerals(Dunn)
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info

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Ask about Hydrotalcite here :
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Print or Cut-and-Paste your Hydrotalcite Specimen Label here :

Hydrotalcite

Mg6Al2(CO3)(OH)16•4(H2O)
Dana No: 16b.06.02.01 Strunz No: 05.DA.50
Locality:

Notes: