Mindat Logo
Home Page Log In Message Board The Mindat Directory
Register Search Pages Mineral Chatroom The Mindat Store

Hilgardite

This page is currently not sponsored. Click here to sponsor this page.
Big Photo

Boulby Mine, Loftus, North Yorkshire, England, UK
© Leon Hupperichs

Show Hilgardite Photos (13)



Formula:
Ca
 
2
B
 
5
O
 
9
Cl · H
 
2
O
System:TriclinicColour:Colorless, light pink; ...
Hardness:5
Member of:Hilgardite Group
Name:
Named for Eugene Woldemar Hilgard (1833-1916), German-American geologist, one of the first to describe the Loiuisiana salt dome deposits.


Hilgardite Group.

Several polytypes are known, as well as Sr-bearing varieties.

Classification of Hilgardite

IMA status:Approved
Strunz 8th edition ID:5/K.04-10
Nickel-Strunz 10th (pending) edition ID:6.ED.05

6 : BORATES
E : Pentaborates
D : Tekto-pentaborates
Dana 7th edition ID:26.5.14.1
Dana 8th edition ID:26.5.14.1

26 : HYDRATED BORATES CONTAINING HYDROXYL OR HALOGEN
5 : Pentaborates
Hey's CIM Ref.:10.1.8/9/10

10 : Borates with other anions
1 : Borates with halide
mindat.org URL:http://www.mindat.org/min-1902.html
Please feel free to link to this page.

Type Occurrence of Hilgardite

Type Locality:Choctaw Salt Dome, Iberville Parish, Louisiana, USA
Year of Discovery:1937
Geological Setting of type material:Salt dome.
Associated Minerals at type locality:
QuartzPyriteMagnesiteHilgardite-3TcHauerite
DolomiteDanburiteCalciteBoraciteAnhydrite

Occurrences of Hilgardite

Geological Setting:Marine evaporite deposits

Physical Properties of Hilgardite

Lustre:Vitreous
Diaphaneity (Transparency):Transparent
Colour:Colorless, light pink; colourless in transmitted light
Streak:White
Hardness (Mohs):5
Cleavage:Perfect
Perfect on the {010}, also on {100} but more difficult to realize.
Fracture:Conchoidal
Density (measured):2.67 - 2.71 g/cm3
Density (calculated):2.69 g/cm3

Crystallography of Hilgardite

Crystal System:Triclinic
Class (H-M):1 - Pedial
Space Group:P1
Cell Parameters:a = 6.297Å, b = 6.464Å, c = 6.565Å
α = 74.24°, β = 61.68°, γ = 61.26°
Ratio:a:b:c = 0.974 : 1 : 1.016
Unit Cell Volume:V 198.5 ų
Z:1
Morphology:Crystals tabular {010}, with a marked hemimorphic aspect.
Comment:1A polytype

Optical Data of Hilgardite

Type:Biaxial (+)
RI values: nα = 1.630 nβ = 1.636 nγ = 1.664
2V:Measured: 35° , Calculated: 52°
Maximum Birefringence:δ = 0.034

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r > v

Chemical Properties of Hilgardite

Formula:
Ca
 
2
B
 
5
O
 
9
Cl · H
 
2
O
Essential elements:B, Ca, Cl, H, O
All elements listed in formula:B, Ca, Cl, H, O

Relationship of Hilgardite to other Species

Member of:Hilgardite Group
Other Members of Group:

- +
Kurgantaite
CaSr[B
 
5
O
 
9
]Cl · H
 
2
O
Leucostaurite
Pb
 
2
[B
 
5
O
 
9
]Cl · 0.5H
 
2
O
Tyretskite
Ca
 
2
B
 
5
O
 
9
OH · H
 
2
O
Related Minerals - Nickel-Strunz Grouping):

- +
6.ED.05Tyretskite
Ca
 
2
B
 
5
O
 
9
OH · H
 
2
O
6.ED.05Kurgantaite
CaSr[B
 
5
O
 
9
]Cl · H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
10.1.1Teepleite
Na
 
2
[B(OH)
 
4
]Cl
10.1.2Bandylite
Cu[B(OH)
 
4
]Cl
10.1.3Berborite
Be
 
2
(BO
 
3
)(OH,F) · H
 
2
O
10.1.4Fluoborite
Mg
 
3
(BO
 
3
)(F,OH)
 
3
10.1.5Boracite
Mg
 
3
(B
 
7
O
 
13
)Cl
10.1.6Karlite
Mg
 
7
(BO
 
3
)
 
3
(OH,Cl)
 
5
10.1.7Shabynite
Mg
 
5
(BO
 
3
)(OH)
 
5
(Cl,OH)
 
2
 · 4H
 
2
O
10.1.11Solongoite
Ca
 
2
(H
 
3
B
 
3
O
 
7
)(OH)Cl
10.1.12Hydrochlorborite
Ca
 
4
B
 
8
O
 
15
Cl
 
2
 · 21H
 
2
O
10.1.13Ekaterinite
Ca
 
2
(B
 
4
O
 
7
)(Cl,OH)
 
2
 · 2H
 
2
O
10.1.14Volkovskite
KCa
 
4
[B
 
5
O
 
8
OH]
 
4
[B(OH)
 
3
]
 
2
Cl · 4H
 
2
O
10.1.15Chelkarite
CaMgB
 
2
O
 
4
(Cl,OH)
 
2
 · 5H
 
2
O Or near, with Cl:OH = 3:1
10.1.16Johachidolite
CaAlB
 
3
O
 
7
10.1.17Satimolite
KNa
 
2
Al
 
4
[Cl|B
 
2
O
 
5
]
 
3
 · 13H
 
2
O
10.1.18Chambersite
Mn
2+
3
(B
 
7
O
 
13
)Cl
10.1.19Congolite
(Fe
2+
 
,Mg)
 
3
(B
 
7
O
 
13
)Cl
10.1.20Ericaite
Fe
2+
3
(B
 
7
O
 
13
)Cl

Other Names for Hilgardite

Synonyms:
Calciumhilgardite-2M(Cc)
Other Languages:
German:Hilgardit
Russian:Хилгардит
Spanish:Hilgardita
Varieties:
StrontiohilgarditeStrontiohilgardite-1Tc

Polytypes for Hilgardite

Polytypes:
Hilgardite-1TcHilgardite-3TcHilgardite-4M

Other Information

Electrical:Piezoelectric
Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Hilgardite

Reference List:

- +
Hurlbut and Taylor (1937) American Mineralogist: 22: 1052-1057.

Taylor (1937) Bulletin of the American Association of Petr. Geol.: 21: 1268.

American Mineralogist (1938): 23: 765-771.

Palache, Charles, Harry Berman & Clifford Frondel (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124pp.: 382-383.

Braitsch, O. (1959) 1Tc-Strontiohilgardite (Ca,Sr)2[B5O9](OH)2Cl and seine Stellung in the Hilgarditgruppe. Beiträge Mineral. und Petrogr.: 6: 233-247. [Abs. in Am. Mineral. 44, 1102: http://www.minsocam.org/ammin/AM44/AM44_1102.pdf]

American Mineralogist (1984): 69: 214.

Ghose, S. (1985) A new nomenclature for the borate minerals in the hilgardite (Ca2B5O9Cl·H2O)-tyretskite (Ca2B5O9OH·H2O) group. American Mineralogist (1985): 70: 636-637.

Rachlin, A.L., Mandarino, J.., Murowchick, B.L., Ramik, R.A., Dunn, P.J., and Bac, M.E. (1986) Mineralogy of hilgardite-4M from evaporites in New Brunswick. Canadian Mneralogist: 24: 689-693.

Burns, P.C. and Hawthorne, F.C. (1994) Refinement of the structure of hilgardite-1A. Acta Crystallographica: C50: 653-655.

Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

Internet Links for Hilgardite

Search Engines:
  • Look for Hilgardite on Google
  • Look for Hilgardite images on Google
    • External Links:
  • Look for Hilgardite on Webmineral
  • Look for Hilgardite on Athena Mineralogy
  • Look for Hilgardite on Wikipedia
  • Look for Hilgardite on Mineralien Atlas
  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Hilgardite details from Handbook of Mineralogy (PDF)
    • Mineral Dealers:
  • Buy fine minerals and gemstones from Pala International
  • By minerals from YourMineralCollection
  • Pricedownminerals.com - Reverse Auctions and Shop
  • SpiriferMinerals.com - high quality low prices
  • Top quality minerals from Kristalle of California
  • Visit the Pueblo Gem and Mineral show, Tucson 2012
  • Find Hilgardite on www.crystalclassics.co.uk
  • High-end worldwide specimens & outstanding customer service
  • Buy from David K Joyce minerals
  • Fine Minerals from Weinrich Minerals, Inc.
  • Buy RARE Minerals from Rocks of Africa
  • Edwards Minerals - Fine Specimens
    • Specimens:The following Hilgardite specimens are currently listed for sale on minfind.com.
    Jobs:
  • Mining & Geology Jobs

    • Localities for Hilgardite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
    Hide Locality List
    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    Canada
     
    • New Brunswick
      • Kings Co.
        • Cardwell Parish
          • Penobsquis
    		Canadian Mineralogist (1996): 34: 657-665.; Canadian Mineralogist (1996): 34: 881-892
        • Hammond Parish
    		P.C. Burns, F.C. Hawthorne, J.A.R. Stirling: Can. Mineral. 30:445-448 (1992); Roulston, B.V. and Waugh, D.C.E. (1981) A borate mineal assemblage from the Penobsquis and Salt Springs evaporite deposits of southern New Brunswick. Canadian Mineralogist: 19: 291-301.
        • Studholm Parish
    		Canadian Mineralogist: 43: 1469-1487.
    Germany
     
    • Lower Saxony
      • Göttingen
        • Reyershausen
    		[Clark, 1993 - "Hey's Mineral Index"]
    Kazakhstan
     
    • Aktobe Province (Aqtöbe Oblysy; Aktubinskaya Oblast')
      • Aksai Valley
    		Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    • Atyrau Province (Atyrau Oblysy; Atyrau Oblast')
      • Atyrau (Gur'yev)
    		Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    Russia
     
    • Eastern-Siberian Region
      • Prebaikalia (Pribaikal'e)
        • Irkutskaya Oblast'
          • Zheleznogorsk
    		Mazurov, M.P., Grishina, S.N., Istomin, V.E., and Titov, A.T. (2007): Geology of Ore Deposits 49(4), 271-284.
    UK
     
    • England
      • North Yorkshire
        • Loftus
    		BMS Collection hilgardite-1TC; UK Journal of Mines and Minerals, No. 14 p4-7
    USA
     
    • Alabama
      • Clarke Co.
    		Rocks & Min.: 64:472.
    • Louisiana
      • Iberville Parish
    		Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 380, 383; Clark, 1993 - "Hey's Mineral Index".; American Mineralogist 23:898
    Mineral and/or Locality
    Search Google
     
    Copyright © Jolyon Ralph and Ida Chau 1993-2011. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Further information contact the Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of hundreds of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
    Current server date and time: 9th Sep 2011 03:38:50
    Mineral and Locality Search
    Mineral:
    and/or Locality:
    Options
    Fade toolbar when not in focusFix toolbar to bottom of page
    Hide Social Media Links
    Slideshow frame delay seconds