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Lookout Pass Thallium prospect, Little Valley, Sheeprock Mts, Tooele Co., Utah, USA

This page kindly sponsored by Norman King
Key
Lock Map
Latitude & Longitude (WGS84): 40° 4' 58'' North , 112° 35' 48'' West
Latitude & Longitude (decimal): 40.08278,-112.59694
GeoHash:G#: 9rpujbc7j
Locality type:Prospect
Köppen climate type:BSk : Cold semi-arid (steppe) climate


The mineral collecting area is not really at Lookout Pass, which is located along Pony Express and Overland Stage Route, but is 3-4 miles south of the pass itself, along a dirt road through Little Valley that requires high vehicle clearance and perhaps an ax or hatchet to clear tree limbs growing across it. The N-S trending Little Valley is labeled on the USGS topographic map, but “Little Valley” has hardly ever been used to refer to this site. West Lookout Hills and East Lookout Hills are on either side of the Valley, but those terms are not on the USGS topographic map. All of these features – East and West Lookout Hills and Little Valley – exist only from the Pony Express and Overland Stage Route for about four miles southward to where the hills and the valley between them lose definition. The area of the prospect presently (August 2014) lies between Lat. 40.078 to 40.088 and Long. -112.594 to -112.600, and is in Secs. 26 and 35, T. 8 S., R. 7 W., Tooele County, Utah.

The thallium minerals have been reported from the west side of Little Valley, in foothills forming the northernmost Sheeprock Mountains. Sheeprock Mountains are a horst-block mountain range in the Basin and Range physiographic province. A thick sequence of Paleozoic sedimentary strata ranging in age from late Precambrian to Mississippian is exposed in this area, dipping generally toward the north. The Cambrian Ajax Dolostone, including shallow-water facies such as oolitic, stromatolitic, and mud-cracked carbonates rich in burrow and crawling marks, forms the host rock. Tertiary decalcification of the carbonates led to extensive brecciation, followed by metasomatic silicification to form a variety of dark-colored (organic-rich) chert known as “jasperoid.” Silicification, mineralization, and concentration of organic material occurred along fault and/or shear zones that cut the strata. The structure in Paleozoic strata is dominated by a conjugate set of shears trending NW-SE and NNE-SSW (green to brown outcrop areas in the geologic map below). The drainage pattern, visible in topographic maps, reflects these trends. The recently active quarry is very near the major, southernmost shear shown on this map.

Thallium minerals in jasperoid were discovered here in 1987 near the site shown by the Mindat icon, but closer to the road through Little Valley. Organic-rich jasperoid containing thallium minerals, radiating sprays of stibnite and stibiconite, and arsenian pyrite suggests this is a Carlin-type deposit, and potential for commercial gold production here has inspired occasional exploratory work. A road for access by drilling rigs was constructed near the original site of specimen collection. Drill-hole cores taken there registered as high as 0.02 oz gold/ton (reported by Miranda Gold Corporation–see reference). Silver was detected by EDS analyses in two samples collected by Norman King in 2011, but no visible silver has been found.

Parapierrotite is the most conspicuous mineral in the dark-gray jasperoid, occurring in isolated, stubby, black crystals up to 2 mm in maximum length. These produce brilliant silvery reflections from cleavage surfaces in bright sunlight. Stibnite is present in similar-appearing cleaved crystals, but these are very elongated and form radiating sprays. Many of the latter are altered to cream-colored stibiconite. Parapierrotite alters initially to inconspicuous reddish-brown kermesite, and later, more alteration produces conspicuous cream-colored hydroxycalcioroméite pseudomorphs that mimic the parapierrotite crystals.

Surfaces of the jasperoid are commonly covered by dull back coatings of the thallium oxide avicennite--another product of the weathering of parapierrotite (thallium is lost during formation of kermesite and hydroxycalcioroméite). The jasperoid is oxidized in places to reddish-brown color from iron oxides and kermesite, and color banding in the oxidized jasperoid produces what lapidarists refer to as "wonderstone." Remnants of still-unaltered parapierrotite (metallic cleavages still visible) can be found locally in the oxidized jasperoid. Generally, the darker color, plus brilliant reflections from parapierrotite cleavage planes, are keys to locating the mineralized zones.

NOTE: Lookout Pass thallium-bearing mineral specimens have a history of little analytical work. Collectors should, therefore, be wary of identities listed on labels.

Norman King, rev. December 2017

Alternative Label Names

This is a list of additional names that have been recorded for mineral labels associated with this locality in the minID database. This may include previous versions of the locality name hierarchy from mindat.org, data entry errors, and it may also include unconfirmed sublocality names or other names that can only be matched to this level.

Thallium Prospect (Lookout Pass), Little Valley, Tooele Co., Utah, USA
Lookout Pass, Tooele Co., Utah, USA
Lookout Pass, Tooele Co, Utah, USA

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


27 valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Arseniosiderite
Formula: Ca2Fe3+3(AsO4)3O2 · 3H2O
Reference: Norman King; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Avicennite
Formula: Tl2O3
Reference: Handbook of Mineralogy; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Baryte
Formula: BaSO4
Reference: Norman King; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Calcite
Formula: CaCO3
Reference: Norman KIng
Celestine ?
Formula: SrSO4
Reference: Norman King; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Cervantite
Formula: Sb3+Sb5+O4
Reference: R&M 68:6 p381-393
'Chert'
Reference: Norman King
Cinnabar
Formula: HgS
Reference: King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
'Clays'
Reference: Norman King
Dolomite
Formula: CaMg(CO3)2
Reference: Norman KIng
Goethite
Formula: α-Fe3+O(OH)
Reference: Norman King
Graphite
Formula: C
Reference: Norman King; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Hematite
Formula: Fe2O3
Reference: Norman King; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Hydroxycalcioroméite
Formula: (Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
Reference: Norman King(photo-id 634925)
Kermesite
Formula: Sb2S2O
Reference: Norman King
'Limonite'
Formula: (Fe,O,OH,H2O)
Marcasite
Formula: FeS2
Reference: Norman King
Parapierrotite
Formula: TlSb5S8
Reference: King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Pierrotite
Formula: Tl2(Sb,As)10S16
Reference: Handbook of Mineralogy; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Pyrite
Formula: FeS2
Reference: Collected by and in the collection of Brent Thorne.; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Quartz
Formula: SiO2
Quartz var: Chalcedony
Formula: SiO2
Reference: Norman King
Rutile
Formula: TiO2
Reference: Norman King
Scorodite ?
Formula: Fe3+AsO4 · 2H2O
Reference: Norman King
Senarmontite
Formula: Sb2O3
Reference: Collected by and in the collection of Brent Thorne.
'Stibiconite'
Formula: Sb3+Sb5+2O6(OH)
Reference: R&M 68:6 p381-393
Stibnite
Formula: Sb2S3
Reference: R&M 68:6 p381-393; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Sulphur
Formula: S8
Reference: Alois Lechner data
Tripuhyite
Formula: Fe3+Sb5+O4
Reference: Norman King; King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Valentinite
Formula: Sb2O3
Reference: Brent Thorne specimens
Vrbaite
Formula: Hg3Tl4As8Sb2S20
Reference: King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.
Weissbergite
Formula: TlSbS2
Reference: King, N. R. (2014, October). THE MINERAL ASSEMBLAGE FROM LOOKOUT PASS AREA, SHEEPROCK MOUNTAINS, TOOELE CO., UTAH. In 2014 GSA Annual Meeting in Vancouver, British Columbia.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Graphite1.CB.05aC
Sulphur1.CC.05S8
Group 2 - Sulphides and Sulfosalts
Cinnabar2.CD.15aHgS
Kermesite2.FD.05Sb2S2O
Marcasite2.EB.10aFeS2
Parapierrotite2.HC.05fTlSb5S8
Pierrotite2.HC.05fTl2(Sb,As)10S16
Pyrite2.EB.05aFeS2
Stibnite2.DB.05Sb2S3
Vrbaite2.HF.20Hg3Tl4As8Sb2S20
Weissbergite2.HD.05TlSbS2
Group 4 - Oxides and Hydroxides
'Avicennite'4.CB.10Tl2O3
'Cervantite'4.DE.30Sb3+Sb5+O4
Goethite4.00.α-Fe3+O(OH)
Hematite4.CB.05Fe2O3
Quartz4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Rutile4.DB.05TiO2
Senarmontite4.CB.50Sb2O3
Stibiconite4.DH.20Sb3+Sb5+2O6(OH)
Tripuhyite4.DB.05Fe3+Sb5+O4
Valentinite4.CB.55Sb2O3
Group 5 - Nitrates and Carbonates
'Calcite'5.AB.05CaCO3
Dolomite5.AB.10CaMg(CO3)2
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
'Baryte'7.AD.35BaSO4
'Celestine' ?7.AD.35SrSO4
Group 8 - Phosphates, Arsenates and Vanadates
'Arseniosiderite'8.DH.30Ca2Fe3+3(AsO4)3O2 · 3H2O
Scorodite ?8.CD.10Fe3+AsO4 · 2H2O
Unclassified Minerals, Rocks, etc.
Chert-
Clays-
Hydroxycalcioroméite-(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
Limonite-(Fe,O,OH,H2O)

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Semi-metals and non-metals
Graphite1.3.6.2C
Sulphur1.3.5.1S8
Group 2 - SULFIDES
AmXp, with m:p = 1:1
Cinnabar2.8.14.1HgS
AmBnXp, with (m+n):p = 2:3
Stibnite2.11.2.1Sb2S3
AmBnXp, with (m+n):p = 1:2
Marcasite2.12.2.1FeS2
Pyrite2.12.1.1FeS2
Oxysulfides
Kermesite2.13.1.1Sb2S2O
Group 3 - SULFOSALTS
ø = 2
Vrbaite3.7.15.1Hg3Tl4As8Sb2S20
Weissbergite3.7.7.1TlSbS2
1 < ø < 2
Parapierrotite3.8.14.1TlSb5S8
Pierrotite3.8.7.1Tl2(Sb,As)10S16
Group 4 - SIMPLE OXIDES
A2X3
Avicennite4.3.8.1Tl2O3
Hematite4.3.1.2Fe2O3
Senarmontite4.3.9.2Sb2O3
Valentinite4.3.11.1Sb2O3
AX2
Cervantite4.4.16.1Sb3+Sb5+O4
Rutile4.4.1.1TiO2
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
AB(XO3)2
Dolomite14.2.1.1CaMg(CO3)2
Group 28 - ANHYDROUS ACID AND NORMAL SULFATES
AXO4
Baryte28.3.1.1BaSO4
Celestine ?28.3.1.2SrSO4
Group 40 - HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
(AB)5(XO4)2·xH2O
Scorodite ?40.4.1.3Fe3+AsO4 · 2H2O
Group 42 - HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
(AB)5(XO4)3Zq·xH2O
Arseniosiderite42.8.4.3Ca2Fe3+3(AsO4)3O2 · 3H2O
Group 44 - ANTIMONATES
A2X2O6(O,OH,F)
'Stibiconite'44.1.1.1Sb3+Sb5+2O6(OH)
AX2O6
Tripuhyite44.2.1.3Fe3+Sb5+O4
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Rocks, etc.
'Chert'-
'Clays'-
Hydroxycalcioroméite-(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
'Limonite'-(Fe,O,OH,H2O)
Quartz
var: Chalcedony
-SiO2

List of minerals for each chemical element

HHydrogen
H ArseniosideriteCa2Fe33+(AsO4)3O2 · 3H2O
H Goethiteα-Fe3+O(OH)
H Hydroxycalcioroméite(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
H Limonite(Fe,O,OH,H2O)
H ScoroditeFe3+AsO4 · 2H2O
H StibiconiteSb3+Sb25+O6(OH)
CCarbon
C CalciteCaCO3
C DolomiteCaMg(CO3)2
C GraphiteC
OOxygen
O ArseniosideriteCa2Fe33+(AsO4)3O2 · 3H2O
O AvicenniteTl2O3
O BaryteBaSO4
O CalciteCaCO3
O CelestineSrSO4
O CervantiteSb3+Sb5+O4
O Quartz (var: Chalcedony)SiO2
O DolomiteCaMg(CO3)2
O Goethiteα-Fe3+O(OH)
O HematiteFe2O3
O Hydroxycalcioroméite(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
O KermesiteSb2S2O
O Limonite(Fe,O,OH,H2O)
O QuartzSiO2
O RutileTiO2
O ScoroditeFe3+AsO4 · 2H2O
O SenarmontiteSb2O3
O StibiconiteSb3+Sb25+O6(OH)
O TripuhyiteFe3+Sb5+O4
O ValentiniteSb2O3
MgMagnesium
Mg DolomiteCaMg(CO3)2
SiSilicon
Si Quartz (var: Chalcedony)SiO2
Si QuartzSiO2
SSulfur
S BaryteBaSO4
S CelestineSrSO4
S CinnabarHgS
S KermesiteSb2S2O
S MarcasiteFeS2
S ParapierrotiteTlSb5S8
S PierrotiteTl2(Sb,As)10S16
S PyriteFeS2
S StibniteSb2S3
S SulphurS8
S VrbaiteHg3Tl4As8Sb2S20
S WeissbergiteTlSbS2
CaCalcium
Ca ArseniosideriteCa2Fe33+(AsO4)3O2 · 3H2O
Ca CalciteCaCO3
Ca DolomiteCaMg(CO3)2
Ca Hydroxycalcioroméite(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
TiTitanium
Ti Hydroxycalcioroméite(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
Ti RutileTiO2
FeIron
Fe ArseniosideriteCa2Fe33+(AsO4)3O2 · 3H2O
Fe Goethiteα-Fe3+O(OH)
Fe HematiteFe2O3
Fe Limonite(Fe,O,OH,H2O)
Fe MarcasiteFeS2
Fe PyriteFeS2
Fe ScoroditeFe3+AsO4 · 2H2O
Fe TripuhyiteFe3+Sb5+O4
AsArsenic
As ArseniosideriteCa2Fe33+(AsO4)3O2 · 3H2O
As PierrotiteTl2(Sb,As)10S16
As ScoroditeFe3+AsO4 · 2H2O
As VrbaiteHg3Tl4As8Sb2S20
SrStrontium
Sr CelestineSrSO4
SbAntimony
Sb CervantiteSb3+Sb5+O4
Sb Hydroxycalcioroméite(Ca,Sb3+)2(Sb5+,Ti)2O6(OH)
Sb KermesiteSb2S2O
Sb ParapierrotiteTlSb5S8
Sb PierrotiteTl2(Sb,As)10S16
Sb SenarmontiteSb2O3
Sb StibiconiteSb3+Sb25+O6(OH)
Sb StibniteSb2S3
Sb TripuhyiteFe3+Sb5+O4
Sb ValentiniteSb2O3
Sb VrbaiteHg3Tl4As8Sb2S20
Sb WeissbergiteTlSbS2
BaBarium
Ba BaryteBaSO4
HgMercury
Hg CinnabarHgS
Hg VrbaiteHg3Tl4As8Sb2S20
TlThallium
Tl AvicenniteTl2O3
Tl ParapierrotiteTlSb5S8
Tl PierrotiteTl2(Sb,As)10S16
Tl VrbaiteHg3Tl4As8Sb2S20
Tl WeissbergiteTlSbS2

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Quaternary - Miocene
0 - 23.03 Ma



ID: 3185380
Cenozoic sedimentary rocks

Age: Cenozoic (0 - 23.03 Ma)

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Pleistocene - Pliocene
0.0117 - 5.333 Ma



ID: 2962586
Alluvial materials, Axtell and Harkers Formations

Age: Cenozoic (0.0117 - 5.333 Ma)

Stratigraphic Name: Axtell Formation; Harkers Formation

Comments: Original map source: Hintze, L.F., Willis, G.C., Laes, D.Y.M., Sprinkel, D.A., and Brown, K.D., 2000, Digital Geologic Map of Utah: Utah Geological Survey, Map 179DM, scale 1:500,000.

Lithology: Major:{unconsolidated alluvium}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Rocks & Minerals (1993) 68(6): 381-393.
King, N.R. (2014) The Mineral Assemblage from Lookout Pass Area, Sheeprock Mountains, Tooele County, Utah, in 2014 GSA Annual Meeting in Vancouver, British Columbia (October 2014).

External Links



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