Mineral Evolution Database

Created and maintained by the Mineral Evolution Project in partnership with RRUFF and mindat.

Mineral locality data provided by mindat.org

The Mineral Evolution database is currently under development.

The goal of this page is to present localities at which the mineral is found, and estimates of the oldest possible geologic age of the minerals at these localities.

Locality Name:
GEMCO Mine, Groote Eylandt, East Arnhem Region, Northern Territory, Australia

Oldest recorded age at locality: 30
Youngest recorded age at locality: 16

mindat Locality ID: 125742
mindat URL: http://www.mindat.org/loc-125742.html

Tectonic Settings:

Total number of sublocalities beneath "GEMCO Mine, Groote Eylandt, East Arnhem Region, Northern Territory, Australia": 0
Total number of bottom-level sublocalities: 0

Latitude: 14°'"S
Longitude: 136°30'0"E
Decimal Degree (lat, lon): -14,136.5

A	This mineral is Anthropogenic.
G	This mineral is directly dated.
B	This mineral is reported as having this age.
Y	This mineral is using an age reported as an element mineralization period.
O	This mineral is using an age calculated from all data at the locality.
R	The age displayed for this mineral originates from a different, non-child locality.
P	The age displayed for this mineral is the range of ages for this mineral at all of this locality's children.
	This mineral's age has not yet been recorded.

Braunite	Clay	Coronadite	Kaolinite	None	Quartz	Ramsdellite	Rutile

Birnessite ()*	Braunite ()*	Chalcophanite ()*	Cryptomelane ()*	Kaolinite ()*
Lithiophorite ()*	Manganite ()*	Nsutite ()*	Pyrolusite ()*	Quartz ()*
Romanèchite ()*	Todorokite ()*	Vernadite ()*

This Mineral list contains entries from this locality, including sub-localities. Minerals in bold are reported by mindat.org as occurring directly at this locality, and do not occur at any children (sublocalities) of this locality.

Elements at this locality, including sub-localities: Al Ba Ca Fe H K Li Mg Mn Na O Si Sr Zn

Elements from minerals reported directly at this locality: Al Ba Ca Fe H K Li Mg Mn Na O Si Sr Zn

Structural Groups for minerals in this locality:
Braunite Clay Coronadite Kaolinite None Quartz Ramsdellite Rutile

13 IMA Minerals at location:

Mineral name	Structural Groups	IMA Formula	Max Age (Ma)	Min Age (Ma)	# of localities containing mineral
Birnessite ()*	None	(Na,Ca,K)_0.6(Mn⁴⁺,Mn³⁺)₂O₄·1.5H₂O	30	16	178
Braunite ()*	Braunite	Mn²⁺Mn³⁺₆O₈(SiO₄)	30	16	483
Chalcophanite ()*	None	ZnMn⁴⁺₃O₇·3H₂O	30	16	197
Cryptomelane ()*	Coronadite	K(Mn⁴⁺₇Mn³⁺)O₁₆	18	16	599
Kaolinite ()*	Clay Kaolinite	Al₂Si₂O₅(OH)₄	30	16	5591
Lithiophorite ()*	None	(Al,Li)(Mn⁴⁺,Mn³⁺)O₂(OH)₂	30	16	210
Manganite ()*	Rutile	Mn³⁺O(OH)	30	16	770
Nsutite ()*	Ramsdellite	Mn²⁺_xMn⁴⁺_1-xO_2-2x(OH)_2x	30	16	121
Pyrolusite ()*	Rutile	MnO₂	30	16	3106
Quartz ()*	Quartz	SiO₂	30	16	61156
Romanèchite ()*	None	(Ba,H₂O)₂(Mn⁴⁺,Mn³⁺)₅O₁₀	30	30	312
Todorokite ()*	None	(Na,Ca,K,Ba,Sr)_1-x(Mn,Mg,Al)₆O₁₂·3-4H₂O	30	16	433
Vernadite ()*	None	(Mn,Fe,Ca,Na)(O,OH)₂·nH₂O	30	16	65

2 Ages assigned to this locality:

	Excel ID	Max Age (Ma)	Min Age (Ma)	Age as listed in reference	Dating Method	Age Interpret	Prioritized?	Sample Source	Sample Num	Run Num	Age from other Locality	Dated Mineral	Minerals explicitely stated as having this age	Age applies to these Elements	MinDat Locality ID	Dated Locality (Max Age)	Location as listed in reference	Reference	Reference DOI	Reference ID	Age Notes
	Scott-EG91_386-0001	18	16	18-16	K-Ar	age of mineralization		whole rock					Cryptomelane	K, Mn, Ba	125742	GEMCO Mine, Groote Eylandt, East Arnhem Region, Northern Territory, Australia	GEMCO Mine	Dammer et al. (1996)	10.2113/gsecongeo.91.2.386	EG91_386	age of precipitation, as a result of chemical weathering through widespread dissolution and in situ replacement of pisoliths and ooliths
	Scott-EG91_386-0002	30	30	30	K-Ar	age of mineralization		whole rock					Romanechite	Mn, Ba	125742	GEMCO Mine, Groote Eylandt, East Arnhem Region, Northern Territory, Australia	GEMCO Mine	Dammer et al. (1996)	10.2113/gsecongeo.91.2.386	EG91_386

Sample	Source Locality	Reference URL

All locality data graciously provided by mindat.org

All age data...