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Neptunite

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Dallas Gem Mine (Benitoite Mine; Benitoite Gem Mine), New Idria District, San Benito Co., California, USA
© fabreminerals.com

Show Neptunite Photos (78)
Formula:
Na
 
2
KLi(Fe
2+
 
,Mn
2+
 
)
 
2
Ti
 
2
[Si
 
8
O
 
24
]
System:MonoclinicColour:Black, deep red brown in ...
Hardness:5 - 6
Name:For Neptune, Roman god of the sea, for close association at type locality with aegirine (scandinavian sea god).
Isostructural with:Manganoneptunite
This page provides mineralogical data about Neptunite.

Classification of Neptunite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/F.37-10
Nickel-Strunz 10th (pending) edition ID:9.EH.05

9 : SILICATES (Germanates)
E : Phyllosilicates
H : Transitional structures between phyllosilicate and other silicate units
Dana 8th edition ID:70.4.1.1

70 : INOSILICATES Column or Tube Structures
4 : Column or Tube Structures with linked chains forming cages
Hey's CIM Ref.:14.9.26

14 : Silicates not Containing Aluminum
9 : Silicates of Ti
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Type Occurrence of Neptunite

Type Locality:Narssârssuk pegmatite (Narsarsuk pegmatite), Narssârssuk (Narsarsuk), Igaliku (Igaliko), Narsaq, Kitaa (West Greenland) Province, Greenland
Year of Discovery:1893

Physical Properties of Neptunite

Lustre:Vitreous
Diaphaneity (Transparency):Opaque
Colour:Black, deep red brown in splinters
Streak:Cinnamon-brown
Hardness (Mohs):5 - 6
Tenacity:Brittle
Cleavage:Perfect
on {110}
Fracture:Conchoidal
Density (measured):3.19 - 3.23 g/cm3
Density (calculated):3.24 g/cm3

Crystallography of Neptunite

Crystal System:Monoclinic
Class (H-M):m - Domatic
Space Group:Bb (B1 1b) [Cc] {C1c1}
Cell Parameters:a = 16.427(2) Å, b = 12.478(2) Å, c = 9.975(1) Å
β = 115.56(1)°
Ratio:a:b:c = 1.316 : 1 : 0.799
Unit Cell Volume:V 1,844.54 ų (Calculated from Unit Cell)
Z:4
Morphology:Prismatic crystals
Twinning:Interpenetrant on {301}
Crystal Atlas:
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Neptunite no.1 - Goldschmidt (1913-1926)
Neptunite no.2 - Goldschmidt (1913-1926)
Neptunite no.3 - Goldschmidt (1913-1926)
Neptunite no.16 - Goldschmidt (1913-1926)

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Optical Data of Neptunite

Type:Biaxial (+)
RI values: nα = 1.690 - 1.691 nβ = 1.693 - 1.700 nγ = 1.719 - 1.736
2V:Measured: 36° to 49°, Calculated: 36° to 56°
Maximum Birefringence:δ = 0.029 - 0.045

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:High
Dispersion:r < v strong
Pleochroism:Visible
Comments:X= pale yellow
Y= yellow-orange
Z= red-orange to red-brown

Chemical Properties of Neptunite

Formula:
Na
 
2
KLi(Fe
2+
 
,Mn
2+
 
)
 
2
Ti
 
2
[Si
 
8
O
 
24
]
Essential elements:Fe, K, Li, Na, O, Si, Ti
All elements listed in formula:Fe, K, Li, Mn, Na, O, Si, Ti
Common Impurities:Ca

Relationship of Neptunite to other Species

Series:Forms a series with Manganoneptunite (see here)
Related Minerals - Nickel-Strunz Grouping):

- +
9.EH.05Manganoneptunite
Na
 
2
KLi(Mn
2+
 
,Fe
2+
 
)
 
2
Ti
 
2
[Si
 
8
O
 
24
]
9.EH.05Watatsumiite
Na
 
2
KLi(Mn
2+
 
,Fe
2+
 
)
 
2
V
4+
2
[Si
 
8
O
 
24
]
9.EH.10Grumantite
Na[Si
 
2
O
 
4
(OH)]·H
 
2
O
9.EH.15Sarcolite
Na
 
2
Ca
 
12
(Ca,K,Fe,Sr,Mg)
 
2
Al
 
8
Si
 
12
(P,Si)O
 
52
F
 
2
9.EH.20Ussingite
Na
 
2
AlSi
 
3
O
 
8
OH
9.EH.25Leifite
(Na,H
 
2
O)Na
 
6
[F
 
2
|Be
 
2
Al
 
2
(Al,Si)Si
 
15
O
 
39
]
9.EH.25Telyushenkoite
(Cs,Na,K)Na
 
6
[F
 
2
|Be
 
2
Al
 
3
Si
 
15
O
 
39
]
9.EH.25Eirikite
KNa
 
6
Be
 
2
(Si
 
15
Al
 
3
)O
 
39
F
 
2
9.EH.30Nafertisite
Na
 
3
(Fe
2+
 
,Fe
3+
 
)
 
6
(Ti
 
2
Si
 
12
O
 
34
)(O,OH)
 
7
·2H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
14.9.1Natisite
Na
 
2
Ti[O|SiO
 
4
]
14.9.2Lorenzenite
Na
 
2
Ti
 
2
[O
 
3
|Si
 
2
O
 
6
]
14.9.3Lintisite
LiNa
 
3
Ti
 
2
[O|Si
 
2
O
 
6
]
 
2
 · 2H
 
2
O
14.9.4Davanite
K
 
2
TiSi
 
6
O
 
15
14.9.5Kazakovite
Na
 
6
Ti[Si
 
6
O
 
16
(OH)
 
2
]
14.9.6Titanite
CaTi[O|SiO
 
4
]
14.9.7Ohmilite
Sr
 
3
(Ti,Fe
3+
 
)[(O,OH)|(Si
 
2
O
 
6
)
 
2
] · 2-3H
 
2
O
14.9.8Lamprophyllite
(Sr,K,Ba)
 
2
(Na,Ti,Mn
2+
 
,Fe
3+
 
)
 
4
Ti
 
2
[O|(O,OH,F)|Si
 
2
O
 
7
]
 
2
14.9.9Benitoite
BaTi[Si
 
3
O
 
9
]
14.9.10Batisite
Na
 
2
BaTi
 
2
[O|Si
 
2
O
 
6
]
 
2
14.9.11Fresnoite
Ba
 
2
Ti[O|Si
 
2
O
 
7
]
14.9.12Joaquinite-(Ce)
Ba
 
2
NaCe
 
2
FeTi
 
2
Si
 
8
O
 
26
(OH,F) · H
 
2
O
14.9.13Orthojoaquinite-(Ce)
Ba
 
2
NaCe
 
2
FeTi
 
2
Si
 
8
O
 
26
(O,OH) · H
 
2
O
14.9.14Strontiojoaquinite
Sr
 
2
Ba
 
2
(Na,Fe)
 
2
Ti
 
2
Si
 
8
O
 
24
(O,OH)
 
2
·H
 
2
O
14.9.15Bario-orthojoaquinite
(Ba,Sr)
 
4
Fe
 
2
Ti
 
2
Si
 
8
O
 
26
·H
 
2
O
14.9.16Strontio-orthojoaquinite
Sr
 
2
Ba
 
2
(Na,Fe)
 
2
Ti
 
2
Si
 
8
O
 
24
(O,OH)
 
2
·H
 
2
O
14.9.17Bafertisite
Ba(Fe
3+
 
,Mn
2+
 
)
 
2
Ti[O|(O,OH)
 
2
|Si
 
2
O
 
7
]
14.9.18Hejtmanite
Ba(Mn
2+
 
,Fe
2+
 
)
 
2
Ti[O|(OH,F)
 
2
|Si
 
2
O
 
7
]
14.9.19Delindeite
(Na,K)
 
2.7
(Ba,Ca)
 
4
(Ti,Fe,Al)
 
6
Si
 
8
O
 
26
(OH)
 
14
14.9.20Barytolamprophyllite
(Ba,Na)
 
2
(Na,Ti,Fe
3+
 
)
 
4
Ti
 
2
[O|(OH,F)|Si
 
2
O
 
7
]
 
2
14.9.21Trimounsite-(Y)
Y
 
2
Ti
 
2
[O
 
5
|SiO
 
4
]
14.9.22Perrierite-(Ce)
(Ce,Ca,Th)
 
4
(Mg,Fe
2+
 
)
 
2
(Ti,Fe
3+
 
)
 
3
[O
 
4
|Si
 
2
O
 
7
]
 
2
14.9.23Chevkinite
(Ca,Ce,Th)
 
4
(Fe,Mn)
 
2
(Ti,Fe)
 
3
Si
 
4
O
 
22
14.9.24Strontiochevkinite
(Sr,La,Ce,Ca)
 
4
Fe
3+
 
(Ti,Zr)
 
2
Ti
 
2
[O
 
4
|Si
 
2
O
 
7
]
 
2
14.9.25Tisinalite
Na
 
3
H
 
3
(Mn,Ca,Fe)TiSi
 
6
(O,OH)
 
18
·2H
 
2
O
14.9.27Manganoneptunite
Na
 
2
KLi(Mn
2+
 
,Fe
2+
 
)
 
2
Ti
 
2
[Si
 
8
O
 
24
]
14.9.28Kupletskite
(K,Na)
 
3
(Mn,Fe)
 
7
Ti
 
2
Si
 
8
O
 
26
(OH)
 
4
F
14.9.29Astrophyllite
(K,Na)
 
3
(Fe,Mn)
 
7
Ti
 
2
Si
 
8
O
 
24
(O,OH)
 
7
14.9.30Hydroastrophyllite
(H
 
3
O,K,Ca)
 
3
(Fe,Mn)
 
5-65
Ti
 
2
Si
 
8
(O,OH)
 
31
14.9.31Magnesioastrophyllite
(Na,K)
 
4
Mg
 
2
(Fe,Fe,Mn)
 
5
Ti
 
2
Si
 
8
O
 
24
(O,OH,F)
 
7
14.9.32Baratovite
KCa
 
7
(Ti,Zr)
 
2
Li
 
3
Si
 
12
O
 
36
F
 
2
14.9.34Aenigmatite
Na
 
2
Fe
2+
5
TiO
 
2
]Si
 
6
O
 
18
]
14.9.35Schorlomite
Ca
 
3
(Ti,Fe
3+
 
)
 
2
[(Si,Fe
3+
 
,Fe
2+
 
)O
 
4
]
 
3
14.9.36Tinaksite
K
 
2
Na(Ca,Mn
2+
 
)
 
2
Ti[O|Si
 
7
O
 
18
(OH)]
14.9.37Janhaugite
(Na,Ca)
 
3
(Mn,Fe)
 
3
(Ti,Zr,Nb)
 
2
Si
 
4
O
 
15
(OH,F,O)
 
3
14.9.38Koashvite
Na
 
6
(Ca,Mn)(Ti,Fe)Si
 
6
O
 
18
·H
 
2
O

Other Names for Neptunite

Synonyms:
CarlositeFerroneptunite
Other Languages:
German:Carlosit
Neptunit
Russian:Нептунит
Spanish:Carlosita
Neptunita

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 Neptunite

Reference List:Hlawatsch, C. (1909), Bemerkungen zum Aragonit von Rohitsch, Natrolit, und Neptunit von S. Benito: Tschermaks Mitt.: Band 28, pp. 293-296, 1909.

Bradley, W.M. (1909), On the analysis of the mineral neptunite from San Benito County, California: Am. Jour. Sci., 4th. Series: 28: 15-16; & Zeitschr. Kristallographie, band 46: 516-517 (1909).

Ford, William Ebenezer (1909), Neptunite crystals from San Benito, California: Am. Jour. Sci., 4th. Series: 27: 235-240; …Zeitschr. Kristallographie, Band 46: 321-325 (1909).

Schaller, Waldemar Theodore (1911), Notes on neptunite: USGS Bull. 490: 55-57.

Schaller, Waldemar Theodore (1911), Krystallographische Notizen ueber Albit, Phenakit, und Neptunit: Zeitschr. Kristallographie, Band 48: 550-558; …USGS Bull. 490: 53-56 (1911).

Berry, Leonard G. (1963b), Neptunite: unit cell and X-ray powder data: Canadian Mineralogist:7: 679-681.

Cannillo, E., F. Mazzi & G. Rossi (1966), The crystal structure of neptunite: Acta Crystallographica: 21: 200-208.

Bancroft, G.M., R.G. Burns & A.G. Maddock (1967), Oxidation state of iron in neptunite from Mossbauer spectroscopy: Acta Crystallographica: 22: 394-395.

Laird, J. & A.L. Albee (1972), Chemical composition and physical, optical, and structural properties of benitoite, neptunite and joaquinite: American Mineralogist: 57: 85-102.

Tschermaks Mineralogische und Petrographische Mitteilungen (1982): 30: 237-247.

Physics and Chemistry of Minerals (1991): 18: 199.

American Mineralogist (1993): 78: 237.

Internet Links for Neptunite

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    Localities for Neptunite

    Hide Locality List
    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.
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    (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.
    Australia
     
    • New South Wales
      • Darling Co.
        • Barraba
    		Slansky, E. & Glen, R. A. (1983): Neptunite from the Woodsreef Serpentinite, New South Wales: a new occurrence. Tschermaks Mineralogische und Petrographische Mitteilungen 30, 237-247; GS 1981/231
    Brazil
     
    • South Region
      • Santa Catarina
    • Southeast Region
      • Minas Gerais
        • Poços de Caldas plateau
          • Poços de Caldas
    		Atencio et al. (1999) Can. Min. 37, 91-98.
    Canada
     
    • Newfoundland and Labrador
      • Labrador
    William Heinrich, E. & Quon, Shi H. (1963): Neptunite from Seal Lake, Labrador. Canadian Mineralogist 7, 650-654.
    • Québec
      • Rouville Co.
        • Mont Saint-Hilaire
    		No reference listed
    Greenland
     
    • Kitaa (West Greenland) Province
      • Narsaq
        • Igaliku (Igaliko)
          • Narssârssuk (Narsarsuk)
    		Geol.Fören.Stockh.Förh.(1893) 15, p. 196; Petersen Ole V.,Secher K.(1985) - Gronland: Mineralien, Geologie, Geschichte. - Verlag Bode & Partner K.G., Bochum, 87 pagg.
        • Ilimaussaq complex
          • Kangerdluarssuq (Kangerdluarssuk; Kangerdluarsuk) Firth
            • Head of Kangerdluarssuq
              • Lilleelv
    		Danoe, M., Soerensen, H. (1959): An examination of the rare minerals from the Nepheline Syenites of south west Greenland, Meddelelser om Groenland, Vol. 162, Nr.5, Reitzels Forlag, Koebenhavn
            • Qeqertaussaq Island
    		Soerensen, H. (1962): On the occurrence of Steenstrupine in the Ilimaussaq massif, southwest Greenland, Meddelelser om Groenland, Reitzels Forlag Koebenhavn
    Friis, H., Balic-Zunic, T, Pekov, I., Peterson, O. (2004): Kuannersuite-(Ce), a new member of the Apatite-group, from the Ilimaussaq alkaline complex, South Greenland, Canadian Mineralogist, Vol. 42, 95-106
    Metcalf-Johansen, J. (1977): Willemite from the Ilimaussaq alkaline Intrusion, Mineralogical Magazine, Vol. 41, 71-75
          • Tasseq area
    		Found by Frank de Wit (2008)
          • Tunugdliarfik Firth (Eriksfjord)
    		Boggild, O.B. (1953): The Mineralogy of Greenland, Reitzels Forlag, Kobenhavn; Soerensen, H. (1962): On the occurence of Steenstrupine in the Ilimaussaq massif, southwest Greenland, Meddelelser om Groenland, Reitzels Forlag Koebenhavn
    Boeggild, O.B. (1953): The Mineralogy of Greenland, Meddelelser om Groenland, Vol. 149/3, Reitzels Forlag Koebenhavn
    Boeggild, O.B. (1953): The Mineralogy of Greenland, Meddelelser om Groenland, Vol. 149/3, Reitzels Forlag Koebenhavn
    Ireland
     
    • Co. Louth
      • Carlingford
    		Nockolds, S. R. (1950): The occurrence of neptunite and eudialyte in quartz-bearing syenites from Barnavave, Carlingford, Ireland. Mineralogical Magazine 29, 27-33.
    Mongolia
     
    • Gobi Desert
    Russia
     
    • Eastern-Siberian Region
      • Saha Republic (Sakha Republic; Yakutia)
        • Aldan Shield
          • Aldan
    		N.V. Chukanov et al.: Zap. Vses. Mineral. Obshch. 133(1):59-72 (2004)
      • Transbaikalia (Zabaykalye)
        • Buriatia (Buryatia) Republic
          • Mama River Basin
            • Maigunda River
    		Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    • Northern Region
      • Murmanskaja Oblast'
        • Kola Peninsula
          • Khibiny Massif
          • Lovozero Massif
    		Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
            • Seidozero Lake
    		Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union 369p. Ocean Pictures, Moscow
    Pavel M. Kartashov data; Semenov E.I. (1972) Mineralogy of Lovozero alkaline massif, - Moscow, Nauka, p. 308 (in Rus.)
    Tajikistan
     
    • Region of Republican Subordination
      • Tien Shan Mts
        • Alai (Alayskiy) Range
    		CanMin 42:107-119 (2004)
    USA
     
    • California
    		No reference listed
    www.mineralsocal.org
        • New Idria District
          • Clear Creek area
    Wise, W.S & Gill, R.H. (1977): Minerals of the Benitoite Gem mine. Mineralogical Record 8, 442-452
    www.benitoitemine.com
    • Montana
      • Meagher Co.
    		Chakhmouradian, A. R. & Mitchell, R. H. (2002): The mineralogy of Ba- and Zr-rich alkaline pegmatites from Gordon Butte, Crazy Mountains (Montana, USA): comparisons between potassic and sodic agpaitic pegmatites. Contributions to Mineralogy and Petrology 143, 93-114.
    • New Mexico
      • Colfax Co.
        • Springer
          • Point of Rocks Mesa (Pecks Mesa)
    		Rocks & Min.:60:229.
    • North Carolina
      • Alexander Co.
    		Collected & identified by Michael Reynolds
    Mineral and/or Locality
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