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Las Choyas, Aldama Municipality, Chihuahua, Mexicoi
Regional Level Types
Las Choyas- not defined -
Aldama MunicipalityMunicipality
ChihuahuaState
MexicoCountry

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Latitude & Longitude (WGS84):
29° North , 105° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~69km
Köppen climate type:


Diggings in a 2 square mile tuffaceous ash flow that produce the "Mexican Coconut" geodes.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


18 valid minerals.

Detailed Mineral List:

Beidellite
Formula: (Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
Habit: stubby fibers
Colour: light gray
Description: found in less then 1% of cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.26
Birnessite
Formula: (Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
Habit: granular fracture filling in calcite
Colour: black
Description: found in less then 1%
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.26
Calcite
Formula: CaCO3
Habit: Scalenohedral, plates
Colour: clear, white
Description: Found in ~50% of all Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.19
Cryptomelane
Formula: K(Mn4+7Mn3+)O16
Habit: fibrous tufts
Colour: black
Description: found in less then 1% of all cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.26
Goethite
Formula: α-Fe3+O(OH)
Habit: globular aggregates, radiating sheath like groups
Colour: black, red, orange, brown
Description: found in 50-75% of Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.20
Gypsum
Formula: CaSO4 · 2H2O
Habit: tabular crystals
Colour: colorless to white
Description: found in less then 1% of all Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Hematite
Formula: Fe2O3
Habit: hemispheres, spheres, rosettes
Colour: black, red, orange, brown
Description: found in 50-75% of the Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.20
Hollandite
Formula: Ba(Mn4+6Mn3+2)O16
Habit: slender needles
Colour: black
Description: found in less then1% of all cocanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.26
Hydroxylapatite
Formula: Ca5(PO4)3(OH)
Habit: hexagonal plates
Colour: colorless to pale green
Description: usually found on hematite spheres Found in less then 1% of Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Hydroxylapatite var: Carbonate-rich Hydroxylapatite
Formula: Ca5(PO4,CO3)3(OH,O)
Habit: hexagonal plates
Colour: colorless to pale green
Description: usually found on hematite spheres Found in less then 1% of Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Kaolinite
Formula: Al2(Si2O5)(OH)4
Habit: hexagonal plates
Colour: white
Description: found in less then 1% of all cocanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Mordenite
Formula: (Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
Habit: masses of fine fibers
Colour: white
Description: found in less then 5% of all Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Opal
Formula: SiO2 · nH2O
Habit: botryoidal
Colour: colorless to white
Description: found in less then 1% of all Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Pyrolusite
Formula: Mn4+O2
Colour: Black to brown
Description: found in 20% of all cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.23
Quartz
Formula: SiO2
Description: found in 90% of all Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.19
Quartz var: Agate
Reference: Karl Volkman
Quartz var: Amethyst
Formula: SiO2
Reference: Karel Bal Collection
Quartz var: Chalcedony
Formula: SiO2
Colour: milky white to blue gray
Description: froms the outer rim of many Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.19
Ramsdellite
Formula: Mn4+O2
Habit: most commonly radiating aggregates
Colour: black
Description: found in ~25% of Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.21
Ranciéite
Formula: (Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
Habit: irregular masses, dendrites, hexagonal plates
Colour: black
Description: generaly associated with secondary calcite, Found in less then 1% of all cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.26
Siderite
Formula: FeCO3
Habit: massive
Colour: brown
Description: froms the outer wall of ~25% of the Cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.19
Todorokite
Formula: (Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Habit: fibrous
Colour: light brown to black
Description: found in ~30% of all cocoanuts
Reference: Cross, B. & Culp Zeitner J. (2006), Geodes Natures Treasures, P.21

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Birnessite4.FL.45(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
Cryptomelane4.DK.05aK(Mn4+7Mn3+)O16
Goethite4.00.α-Fe3+O(OH)
Hematite4.CB.05Fe2O3
Hollandite4.DK.05aBa(Mn4+6Mn3+2)O16
Opal4.DA.10SiO2 · nH2O
Pyrolusite4.DB.05Mn4+O2
Quartz4.DA.05SiO2
var: Agate4.DA.05SiO2
var: Amethyst4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Ramsdellite4.DB.15aMn4+O2
Ranciéite4.FL.40(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
Todorokite4.DK.10(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Siderite5.AB.05FeCO3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Gypsum7.CD.40CaSO4 · 2H2O
Group 8 - Phosphates, Arsenates and Vanadates
Hydroxylapatite8.BN.05Ca5(PO4)3(OH)
var: Carbonate-rich Hydroxylapatite8.BN.05Ca5(PO4,CO3)3(OH,O)
Group 9 - Silicates
Beidellite9.EC.40(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
Kaolinite9.ED.05Al2(Si2O5)(OH)4
Mordenite9.GD.35(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O

List of minerals arranged by Dana 8th Edition classification

Group 4 - SIMPLE OXIDES
A2X3
Hematite4.3.1.2Fe2O3
AX2
Pyrolusite4.4.1.4Mn4+O2
Ramsdellite4.4.7.1Mn4+O2
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 7 - MULTIPLE OXIDES
(AB)2X3
Birnessite7.5.3.1(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
AB3X7
Todorokite7.8.1.1(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
AB8X16
Cryptomelane7.9.1.2K(Mn4+7Mn3+)O16
Hollandite7.9.1.1Ba(Mn4+6Mn3+2)O16
AB4X9
Ranciéite7.10.1.1(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Siderite14.1.1.3FeCO3
Group 29 - HYDRATED ACID AND NORMAL SULFATES
AXO4·xH2O
Gypsum29.6.3.1CaSO4 · 2H2O
Group 41 - ANHYDROUS PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
A5(XO4)3Zq
Hydroxylapatite41.8.1.3Ca5(PO4)3(OH)
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 clays
Beidellite71.3.1a.1(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Si Tetrahedral Frameworks - SiO2 with H2O and organics
Opal75.2.1.1SiO2 · nH2O
Group 77 - TECTOSILICATES Zeolites
Zeolite group - True zeolites
Mordenite77.1.6.1(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
Unclassified Minerals, Mixtures, etc.
Hydroxylapatite
var: Carbonate-rich Hydroxylapatite
-Ca5(PO4,CO3)3(OH,O)
Kaolinite-Al2(Si2O5)(OH)4
Quartz
var: Agate
-SiO2
var: Amethyst-SiO2
var: Chalcedony-SiO2

List of minerals for each chemical element

HHydrogen
H Goethiteα-Fe3+O(OH)
H Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
H Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
H KaoliniteAl2(Si2O5)(OH)4
H Hydroxylapatite (var: Carbonate-rich Hydroxylapatite)Ca5(PO4,CO3)3(OH,O)
H GypsumCaSO4 · 2H2O
H OpalSiO2 · nH2O
H Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
H Birnessite(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
H Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
H HydroxylapatiteCa5(PO4)3(OH)
CCarbon
C CalciteCaCO3
C SideriteFeCO3
C Hydroxylapatite (var: Carbonate-rich Hydroxylapatite)Ca5(PO4,CO3)3(OH,O)
OOxygen
O CalciteCaCO3
O QuartzSiO2
O Quartz (var: Chalcedony)SiO2
O SideriteFeCO3
O HematiteFe2O3
O Goethiteα-Fe3+O(OH)
O Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
O RamsdelliteMn4+O2
O PyrolusiteMn4+O2
O Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
O KaoliniteAl2(Si2O5)(OH)4
O Hydroxylapatite (var: Carbonate-rich Hydroxylapatite)Ca5(PO4,CO3)3(OH,O)
O GypsumCaSO4 · 2H2O
O OpalSiO2 · nH2O
O Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
O Birnessite(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
O Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
O CryptomelaneK(Mn74+Mn3+)O16
O HollanditeBa(Mn64+Mn23+)O16
O Quartz (var: Amethyst)SiO2
O HydroxylapatiteCa5(PO4)3(OH)
NaSodium
Na Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Na Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
Na Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
Na Birnessite(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
MgMagnesium
Mg Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
AlAluminium
Al Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Al Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
Al KaoliniteAl2(Si2O5)(OH)4
Al Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
SiSilicon
Si QuartzSiO2
Si Quartz (var: Chalcedony)SiO2
Si Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
Si KaoliniteAl2(Si2O5)(OH)4
Si OpalSiO2 · nH2O
Si Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
Si Quartz (var: Amethyst)SiO2
PPhosphorus
P Hydroxylapatite (var: Carbonate-rich Hydroxylapatite)Ca5(PO4,CO3)3(OH,O)
P HydroxylapatiteCa5(PO4)3(OH)
SSulfur
S GypsumCaSO4 · 2H2O
KPotassium
K Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
K Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
K CryptomelaneK(Mn74+Mn3+)O16
CaCalcium
Ca CalciteCaCO3
Ca Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Ca Mordenite(Na2,Ca,K2)4(Al8Si40)O96 · 28H2O
Ca Hydroxylapatite (var: Carbonate-rich Hydroxylapatite)Ca5(PO4,CO3)3(OH,O)
Ca GypsumCaSO4 · 2H2O
Ca Beidellite(Na,Ca0.5)0.3Al2((Si,Al)4O10)(OH)2 · nH2O
Ca Birnessite(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
Ca Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
Ca HydroxylapatiteCa5(PO4)3(OH)
MnManganese
Mn Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Mn RamsdelliteMn4+O2
Mn PyrolusiteMn4+O2
Mn Birnessite(Na,Ca)0.5(Mn4+,Mn3+)2O4 · 1.5H2O
Mn Ranciéite(Ca,Mn2+)0.2(Mn4+,Mn3+)O2 · 0.6H2O
Mn CryptomelaneK(Mn74+Mn3+)O16
Mn HollanditeBa(Mn64+Mn23+)O16
FeIron
Fe SideriteFeCO3
Fe HematiteFe2O3
Fe Goethiteα-Fe3+O(OH)
SrStrontium
Sr Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
BaBarium
Ba Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Ba HollanditeBa(Mn64+Mn23+)O16

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Cross, B. & Culp Zeitner J. (2006): Geodes Natures Treasures, P.11-41
Finkelman, R.B., H.T. Evans, and J.J. Matzko, (1974): Manganese minerals in geodes from Chihuahua, Mexico. Mineralogical Magazine, MARCH 1974, VOL. 39, PP. 549-58.
Hoffmann-Rothe, R. (2006): "Coconuts": Die Knack-Geoden von Las Choyas, Mexiko. LAPIS 31 (11), 47-50
Robert B. Finkelman, John J. Matzko, Ching Chang Woo, John Sampson White & Walter R. Brown (1972): A Scanning Electron Microscopy Study of Minerals in Geodes from Chihuahua, Mexico. Mineralogical Record 3:205-212.
Smith, Jeffrey R. (2010) The Las Choyas Geode Deposit. Rocks & Minerals, 85:112-122


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