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Arakawa River, Nagatoro, Chichibu District, Saitama Prefecture, Japani
Regional Level Types
Arakawa RiverRiver Valley
NagatoroTown
Chichibu DistrictDistrict
Saitama PrefecturePrefecture
JapanCountry

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Latitude & Longitude (WGS84):
36° 6' 8'' North , 139° 6' 42'' East
Latitude & Longitude (decimal):
36.10223,139.11183
GRN:
N25E80
Type:
River Valley
Köppen climate type:
Cfa : Humid subtropical climate
Mindat Locality ID:
484070
Long-form identifier:
mindat:1:2:484070:4
GUID (UUID V4):
0


All samples were collected from a boulder (1.80 m × 3.45 m × 1.60 m) of hematite-quartz schist, which was one of the largest found, on the bank of the Arakawa River in the Nagatoro area. Around this boulder, basic schist is distributed along the river. Although its size suggests that the boulder fell from a cliff near the sampling site and is therefore inferred to be autochthonous, direct structural continuity with the host schists was not established in the field. However, the mineral assemblages in the samples described below indicate low-temperature metamorphism, which is consistent with that of the surrounding metamorphic rocks in the Nagatoro area. The hematite-quartz schist is composed mainly of alternating pelitic and siliceous layers, and calcite veins sometimes cut the structure. The pelitic and siliceous layers are typically 2–6 cm and 2–4 cm thick, respectively.

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Mineral List


11 valid minerals.

Rock Types Recorded


Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

ⓘ Actinolite
Formula: ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
ⓘ Aegirine
Formula: NaFe3+Si2O6
ⓘ Albite
Formula: Na(AlSi3O8)
ⓘ 'Amphibole Supergroup'
Formula: AB2C5(T8O22)W2
ⓘ Ankerite
Formula: Ca(Fe2+,Mg)(CO3)2
ⓘ 'Apatite'
Formula: Ca5(PO4)3A
ⓘ Augite
Formula: (CaxMgyFez)(Mgy1Fez1)Si2O6
ⓘ Calcite
Formula: CaCO3
ⓘ Clinochlore
Formula: Mg5Al(AlSi3O10)(OH)8
ⓘ 'Clinopyroxene Subgroup'
ⓘ Hematite
Formula: Fe2O3
ⓘ 'Limonite'
ⓘ Piemontite
Formula: (CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
ⓘ Quartz
Formula: SiO2
ⓘ Winchite
Formula: ◻(CaNa)(Mg4Al)(Si8O22)(OH)2

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
ⓘHematite4.CB.05Fe2O3
ⓘQuartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
ⓘCalcite5.AB.05CaCO3
ⓘAnkerite5.AB.10Ca(Fe2+,Mg)(CO3)2
Group 9 - Silicates
ⓘPiemontite9.BG.05a(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
ⓘAugite9.DA.15(CaxMgyFez)(Mgy1Fez1)Si2O6
ⓘAegirine9.DA.25NaFe3+Si2O6
ⓘActinolite9.DE.10◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
ⓘWinchite9.DE.20◻(CaNa)(Mg4Al)(Si8O22)(OH)2
ⓘClinochlore9.EC.55Mg5Al(AlSi3O10)(OH)8
ⓘAlbite9.FA.35Na(AlSi3O8)
Unclassified
ⓘ'Amphibole Supergroup'-AB2C5(T8O22)W2
ⓘ'Limonite'-
ⓘ'Clinopyroxene Subgroup'-
ⓘ'Apatite'-Ca5(PO4)3A

List of minerals for each chemical element

HHydrogen
Hⓘ Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
Hⓘ ClinochloreMg5Al(AlSi3O10)(OH)8
Hⓘ Piemontite(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
Hⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
CCarbon
Cⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Cⓘ CalciteCaCO3
OOxygen
Oⓘ Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
Oⓘ AegirineNaFe3+Si2O6
Oⓘ AlbiteNa(AlSi3O8)
Oⓘ Amphibole SupergroupAB2C5(T8O22)W2
Oⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Oⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Oⓘ CalciteCaCO3
Oⓘ ClinochloreMg5Al(AlSi3O10)(OH)8
Oⓘ HematiteFe2O3
Oⓘ Piemontite(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
Oⓘ QuartzSiO2
Oⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
Oⓘ ApatiteCa5(PO4)3A
NaSodium
Naⓘ AegirineNaFe3+Si2O6
Naⓘ AlbiteNa(AlSi3O8)
Naⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
MgMagnesium
Mgⓘ Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
Mgⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Mgⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Mgⓘ ClinochloreMg5Al(AlSi3O10)(OH)8
Mgⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
AlAluminium
Alⓘ AlbiteNa(AlSi3O8)
Alⓘ ClinochloreMg5Al(AlSi3O10)(OH)8
Alⓘ Piemontite(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
Alⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
SiSilicon
Siⓘ Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
Siⓘ AegirineNaFe3+Si2O6
Siⓘ AlbiteNa(AlSi3O8)
Siⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Siⓘ ClinochloreMg5Al(AlSi3O10)(OH)8
Siⓘ Piemontite(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
Siⓘ QuartzSiO2
Siⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
PPhosphorus
Pⓘ ApatiteCa5(PO4)3A
CaCalcium
Caⓘ Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
Caⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Caⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Caⓘ CalciteCaCO3
Caⓘ Piemontite(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
Caⓘ Winchite◻(CaNa)(Mg4Al)(Si8O22)(OH)2
Caⓘ ApatiteCa5(PO4)3A
MnManganese
Mnⓘ Piemontite(CaCa)(AlAlMn3+)O[Si2O7][SiO4](OH)
FeIron
Feⓘ Actinolite◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22(OH)2
Feⓘ AegirineNaFe3+Si2O6
Feⓘ AnkeriteCa(Fe2+,Mg)(CO3)2
Feⓘ Augite(CaxMgyFez)(Mgy1Fez1)Si2O6
Feⓘ HematiteFe2O3

Other Regions, Features and Areas containing this locality

AsiaContinent
Eurasian Plate
Japan
Okhotsk PlateTectonic Plate

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References

[1]Yano, Moei; Yasukawa, Kazutaka; Nozaki, Tatsuo; Fujinaga, Koichiro; Ogasawara, Mitsuki; Nakamura, Kentaro; Iwamori, Hikaru; Kato, Yasuhiro (2027) Geochemistry of hematite-quartz schist in the Sanbagawa metamorphic belt, Japan: A metamorphosed umber deposit. Journal of Geochemical Exploration, 292. p.108246. doi:10.1016/j.gexplo.2026.108246
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