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John W. Searles
White, light brown
Vitreous, Pearly
Specific Gravity:
2.44 - 2.46
Crystal System:
Named after John Wemple Searles (November 16, 1828 Tribes Hill, New York - October 7, 1897 St. Helena, California), California pioneer and discoverer of Searles Lake, USA
The structure of Searlesite contains sheets, consisting of kinked pyroxene-like polysilicate chains that are linked by (H2BO4) tetrahedra, classifying it as a phyllo-borosilicate. The silicate chains contain two crystallographically distinct Si sites, and the net formula of the anion is (H2BSi2O7)n with (H2BSi2O7) as repeating unit (Ghose and Wan, 1976). Note that we are using a sum formula for the anion. It may also be written as (BSiO5(OH)2), indicating that the two protons are bonded to oxygen atoms.

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Classification of SearlesiteHide

Approved, 'Grandfathered' (first described prior to 1959)

9 : SILICATES (Germanates)
E : Phyllosilicates
F : Single nets with 6-membered rings, connected by M[4], M[8], etc.

71 : PHYLLOSILICATES Sheets of Six-Membered Rings
3 : Sheets of 6-membered rings with 2:1 clays

17 : Silicates Containing other Anions
5 : Borosilicates

Physical Properties of SearlesiteHide

Vitreous, Pearly
Vitreous, slightly pearly on cleavage surfaces
White, light brown
3½ on Mohs scale
Perfect on {100}, imperfect on {102}, {010}
2.44 - 2.46 g/cm3 (Measured)    2.46 g/cm3 (Calculated)

Optical Data of SearlesiteHide

Biaxial (-)
RI values:
nα = 1.516 nβ = 1.531 nγ = 1.535
Measured: 55°
Max Birefringence:
δ = 0.019
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:

Chemical Properties of SearlesiteHide

IMA Formula:
Common Impurities:

Crystallography of SearlesiteHide

Crystal System:
Class (H-M):
2 - Sphenoidal
Space Group:
Cell Parameters:
a = 7.9814(12) Å, b = 7.0657(8) Å, c = 4.9054(4) Å
β = 93.95(1)°
a:b:c = 1.13 : 1 : 0.694
Unit Cell V:
275.98 ų (Calculated from Unit Cell)
Flat crystals, to 17 cm, occur along bedding planes. Commonly as spherulitic aggregates of radiating acicular to prismatic crystals; as massive
granular aggregates.

X-Ray Powder DiffractionHide

Powder Diffraction Data:
8.01 (100)
4.06 (50)
3.48 (40)
3.24 (40)
4.31 (30)
3.54 (30)
3.21 (30)

Type Occurrence of SearlesiteHide

Place of Conservation of Type Material:
Harvard University, Cambridge, Massachusetts, 81274; National Museum of Natural History, Washington, D.C., USA, R6457, 93270, 94734, 96080, 124352.
Geological Setting of Type Material:
Boron bearing playa deposits

Other Language Names for SearlesiteHide

Simplified Chinese:水硅硼钠石
Traditional Chinese:水矽硼鈉石

Common AssociatesHide

Associated Minerals Based on Photo Data:
Loughlinite6 photos of Searlesite associated with Loughlinite on
Aegirine1 photo of Searlesite associated with Aegirine on

Related Minerals - Nickel-Strunz GroupingHide

9.EF.05PetaliteLiAl(Si4O10)Mon. 2/m : P2/b
9.EF.20SilinaiteNaLiSi2O5 · 2H2OMon. 2/m
9.EF.25KanemiteHNaSi2O5 · 3H2OOrth. mmm (2/m 2/m 2/m) : Pnma
9.EF.30Yakovenchukite-(Y)K3NaCaY2[Si12O30] · 4H2OOrth. mmm (2/m 2/m 2/m) : Pcca

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

17.5.5ElbaiteNa(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3(OH)Trig. 3m : R3m
17.5.8PoudretteiteKNa2B3Si12O30Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
17.5.9LiddicoatiteCa(Li2Al)Al6(Si6O18)(BO3)3(OH)3(OH)Trig. 3m : R3m
17.5.10DatoliteCaB(SiO4)(OH)Mon. 2/m : P21/b
17.5.11DanburiteCaB2Si2O8Orth. mmm (2/m 2/m 2/m)
17.5.12HowliteCa2B5SiO9(OH)5Mon. 2/m : P21/b
17.5.13BakeriteCa4(H5B5Si3O20)Mon. 2/m : P21/b
17.5.14OyeliteCa10Si8B2O29 · 12.5H2OOrth.
17.5.15KornerupineMg3Al6(Si,Al,B)5O21(OH)Orth. mmm (2/m 2/m 2/m)
17.5.16HarkeriteCa12Mg4Al(BO3)3(SiO4)4(CO3)5 · H2OTrig. 3m (3 2/m) : R3m
17.5.17SerendibiteCa4[Mg6Al6]O4[Si6B3Al3O36]Tric. 1 : P1
17.5.24Cappelenite-(Y)Ba(Y,Ce)6Si3B6O24F2Trig. 3 : P3
17.5.25Dumortierite(Al,Fe3+)7(SiO4)3(BO3)O3Orth. mmm (2/m 2/m 2/m)
17.5.26Holtite(Ta0.60.4)Al6BSi3O18(O,OH)2.25Orth. mmm (2/m 2/m 2/m) : Pnma
17.5.27DraviteNa(Mg3)Al6(Si6O18)(BO3)3(OH)3(OH)Trig. 3m : R3m
17.5.28 FerridraviteNaFe3+3(Mg2Fe3+4)(Si6O18)(BO3)3(OH)3O
17.5.30Uvite SeriesCa(Mg3)MgAl5(Si6O18)(BO3)3(OH)3(F/OH)Trig. 3m : R3m
17.5.32TienshaniteKNa3Na6Ca2Ba6Mn6(Ti4+,Nb)6B12Si36O114(O,OH,F)11Hex. 6/m : P6/m
17.5.34TaramelliteBa4(Fe3+,Ti,Fe2+,Mg)4(B2Si8O27)O2ClxOrth. mmm (2/m 2/m 2/m) : Pmmn
17.5.36NagashimaliteBa4(V,Ti)4B2Si8O27(O,OH)2ClOrth. mmm (2/m 2/m 2/m) : Pmmn
17.5.40Axinite-(Mn)Ca2Mn2+Al2BSi4O15(OH)Tric. 1 : P1
17.5.44SchorlNa(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)Trig. 3m : R3m
17.5.45Fluor-buergeriteNa(Fe3+3)Al6(Si6O18)(BO3)3O3FTrig. 3m : R3m
17.5.46FeruviteCa(Fe2+)3MgAl5(Si6O18)(BO3)3(OH)3(OH)Trig. 3m : R3m
17.5.47Axinite-(Fe)Ca2Fe2+Al2BSi4O15OHTric. 1 : P1
17.5.49Grandidierite(Mg,Fe2+)(Al,Fe3+)3(SiO4)(BO3)O2Orth. mmm (2/m 2/m 2/m)
17.5.50Hyalotekite(Pb,Ba,K)4(Ca,Y)2(B,Be)2(Si,B)2Si8O28(F,Cl)Tric. 1 : P1
17.5.51Hellandite-(Y)(Ca,REE)4Y2Al◻2(B4Si4O22) (OH)2Mon.

Fluorescence of SearlesiteHide

may fluoresce green under SW UV.

Other InformationHide

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

References for SearlesiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Larsen, E.S. & W.B. Hicks (1914) Searlesite, a new mineral, San Bernardino County, California, American Journal of Science, 4th. Series: 38: 437-440.
Ghose, S., and Wan, C. (1976): Structural chemistry of borosilicates, part II:
Searlesite, NaBSi2O5(OH): Absolute configuration, hydrogen locations, and refinement of the structure. American Mineralogist 61, 123-129. [NOTE: The title of the paper gives a wrong formula, in which a sub-script is missing]
Grew, E.S., and Anovitz, L.M. (1996) BORON: Mineralogy, Petrology and Geochemistry, second edition, as revised (2002).

Internet Links for SearlesiteHide

Localities for SearlesiteHide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Salta
    • Los Andes department
      • Salar del Hombre Muerto
Bull. Soc. Franç. Minéralo. Cristallo. , 1974, 97, p. 497.; Alonso, R. N. (1999). On the origin of La Puna borates. Acta geológica hispánica, 34(2), 141-166.; CAHIT HELVACI & RICARDO N. ALONSO (2000) Borate Deposits of Turkey and Argentina; A Summary and Geological Comparison. Turkish Journal of Earth Sciences, 9:1-27.
Bosnia and Herzegovina
  • Federation of Bosnia and Herzegovina
    • Tuzla Canton
      • Tuzla
Am Min 79: pp 562-569
  • Québec
    • Montérégie
      • La Vallée-du-Richelieu RCM
        • Mont Saint-Hilaire
Horváth, L and Gault, R.A. (1990), The mineralogy of Mont Saint-Hilaire Quebec. Mineralogical Record: 21: 284-359.
  • Western Desert
Marchesini, M. & Barresi, A. (2009): I minerali di Wadi natrun, Deserto Occidentale, Egitto, Rivista Mineralogica Italiana, 4/2009, 228-258.
  • Northern Region
    • Murmanskaya Oblast'
      • Lovozero Massif
[World of Stones 95:5-6, p64]
  • Mačva District
    • Loznica
Stanley, C.J., Jones, G.C., Rumsey, M.S., Blake, C., Roberts, A.C., Stirling, J.A.R., Carpenter, G.J.C., Whitfield, P.S., Grice, J.D., LePage, Y. (2007): Jadarite, LiNaSiB3O7(OH), a new mineral species from the Jadar Basin, Serbia. European Journal of Mineralogy, 19, 575-580.
  • Raška District
    • Raška
      • Jarandol Basin
        • Baljevac na Ibru
          • Bella Stena (Bela Stena)
Econ Geol (1992) 87:2169-2174
  • Region of Republican Subordination
    • Tien Shan Mtn
      • Alai Range (Alayskiy)
  • Central Anatolia Region
    • Ankara Province
Helvaci, C., Mordogan, H., Çolak, M., & Gündogan, I. (2004). Presence and distribution of lithium in borate deposits and some recent lake waters of west-central Turkey. International Geology Review, 46(2), 177-190.
    • Eskişehir Province
      • Kirka
García-Veigas, J., & Helvacı, C. (2013). Mineralogy and sedimentology of the Miocene Göcenoluk borate deposit, Kırka district, western Anatolia, Turkey. Sedimentary Geology, 290, 85-96.
Koçak, İ. & Koç, Ş. (2016): Geochemical characteristics of Kırka (Sarıkaya) borate deposit, northwestern Anatolia, Turkey. Journal of Earth System Science: 125: 147-164; (2016)
  • California
    • Inyo Co.
        • Furnace Creek
McAllister, James Franklin (1970) Geology of the Furnace Creek borate area, Death Valley, Inyo County, California. California Division of Mines and Geology Map Sheet 14, 9 pp.: 9; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 511.
      • Lake Tecopa Basin
USGS (2005), Mineral Resources Data System (MRDS): U.S. Geological Survey, Reston, Virginia, loc. file ID #10100710.
      • Saratoga District (Tecopa Mountain District; Shoshone District ?)
        • Dublin Hills
          • Shoshone
U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
    • Kern Co.
      • China Lake [town]
        • China Lake
Hay, Richard Le Roy (1966) Zeolites and zeolitic reactions in sedimentary rocks: Geological Society of America Special Paper 85, 130 p.: 35; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 512.
      • Kramer District (Kramer Borate District)
Rock Currier collection
Smith, George Irving, Hy Almond, & D.L. Sawyer, Jr. (1958), Sassolite from the Kramer borate district, California: American Mineralogist: 43: 1070; Pemberton, H. Earl, Wm. Moller, Jack Schwartz & George Masimer (1960), The minerals of Boron, California, 40 pp. (Published by the Mineral Research Society of California, Montebello, CA): 31; Morgan, V. and Erd, R.C. (1969) Minerals of the Kramer borate district, California California Division of Mines and Geology Mineral Information Service: 22(9&10): 166; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 512.
Smith, George Irving, Hy Almond, & D.L. Sawyer, Jr. (1958), Sassolite from the Kramer borate district, California: American Mineralogist: 43: 1070; Pemberton, H. Earl, Wm. Moller, Jack Schwartz & George Masimer (1960), The minerals of Boron, California, 40 pp. (Published by the Mineral Research Society of California, Montebello, CA): 31; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 333.
Wise, W. S., & Kleck, W. D. (1988). Sodic clay-zeolite assemblage in basalt at Boron, California. Clays and Clay Minerals, 36(2), 131-136.
Tschernich, R. (1992): Zeolites of the World, 64, 311; Richard Dale Collection; Clays and Clay Minerals, Vol. 36, No. 2, 131-136, 1988.
            • West Baker
Am Min 49:543-555
    • San Bernardino Co.
Hay, Richard Le Roy & Richard J. Moiola (1962), Authigenic silicate minerals in Pleistocene sediments of Searles Lake, California (abstract): Geological Society of America Special Paper 73: 168; …Sedimentology: 2: 324; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 118, 333; American Mineralogist (1950): 35: 1014.; Gale, Hoyt Stoddard (1915), Mineralogy of the Searles Lake deposits in Salines in the Owens, Searles, and Panamint basins, southeastern California: USGS Bulletin 580: 296-308
Larsen, Esper Signius & W.B. Hicks (1914), Searlesite, a new mineral, San Bernardino County, California: American Journal of Science, 4th. series: 38: 437-440; Gale, Hoyt Stoddard (1915), Salines in the Owens, Searles, and Panamint basins, southeastern California: USGS Bulletin 580: 292; Rogers, Austin Flint (1924a), The crystallography of searlesite: American Journal of Science, 5th. Series: 7: 498-502; Murdoch, Joseph & Robert W. Webb (1966), Minerals of California, Centennial Volume (1866-1966): California Division Mines & Geology Bulletin 189: 333; Pemberton, H. Earl (1983), Minerals of California; Van Nostrand Reinholt Press: 512.
  • Colorado
    • Garfield Co.
      • Piceance Basin
Minerals of Colorado (1997) E.B. Eckel
    • Rio Blanco Co.
      • Piceance Basin
        • Green River Formation
Minerals of Colorado (1997) E.B. Eckel
      • Piceance Creek Basin
Minerals of Colorado (1997) E.B. Eckel
  • Nevada
AmMin 19:268
Rocks & Minerals, Nov. 1999
NBMG Spec. Pub. 31 Minerals of Nevada
      • Fish Lake Marsh
American Mineralogist 19:268-274
      • Silver Peak Range
NBMG Spec. Pub. 31 Minerals of Nevada
    • Mineral Co.
NBMG Spec. Pub. 31 Minerals of Nevada; Tschernich, R. (1992): Zeolites of the World, 66; American Mineralogist,Vol.49:1366-1387; Cahit Helvaci, Federico Ortí, Javier García-Veigas, Laura Rosell, Ibrahim Gündoğan (2012). Neogene Borate Deposits: Mineralogy, Petrology and Sedimentology; A workshop with special emphasis on the Anatolian deposits International Earth Science Colloquium on the Aegean Region (IESCA-2012, İzmir, Turkey). 64pp.
  • New Mexico
    • Colfax Co.
      • Springer
        • Point of Rocks Mesa (Pecks Mesa)
Rocks & Min.:60:229.; 4th Annual New Mexico Mineral Symposium (1985) New Mexico Geology 7:18-19
  • Utah
    • Duchesne Co.
Am Min 44:326-327; Am Min 58:211-217
UGMS Bull 117 Minerals and Mineral Localities of Utah
Am Min 45:188-199
    • Uintah Co.
UGMS Bull 117 Minerals and Mineral Localities of Utah
      • Uteland Knoll District (Ouray District)
        • Ouray
Am Min 41:672
  • Wyoming
    • Sweetwater Co.
      • Green River formation
Am Min 46:420-429
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