Dan Polhemus' Photo Gallery

JH5-61KGranite

Conger Mine, Boulder County Tungsten Mining District, Boulder County, Colorado, USA

Dimensions: 7.8 mm x 6.5 mm

Wall rock from the Conger Mine, consisting of black hornblende monzonite porphyry cut by a white vein of what the older literature on the mine terms "alaskite" but which is now more properly referred to as an alkali-feldspar granite, containing predominantly quartz and pale alkali feldspars.

Collected from the dumps on 22 July 2023; currently in the Polhemus collection, catalog # POL-MIN-2023-0195.

Dan A. Polhemus photo, 2023.

U53-HQCSchist

Conger Mine, Boulder County Tungsten Mining District, Boulder County, Colorado, USA

Dimensions: 9.2 cm x 4.5 cm

Wall rock from the Conger Mine, consisting of densely garnetiferous quartz-biotite schist of the Idaho Springs Formation, representing metamorphosed layers of ancient shale and interbedded sandstone. This is one of the oldest geologic units in Colorado, with an age in excess of 1 billion years, and forms the wall rock around the southwestern side of the Conger Mine deposit. The density of red garnets in this sample is atypical of the Idaho Springs formation as a whole.

Collected from the dumps on 22 July 2023; currently in the Polhemus collection, catalog # POL-MIN-2023-0194.

Dan A. Polhemus photo, 2023.

3T1-VFPFerberite FeWO₄ , Quartz SiO₂

Conger Mine, Boulder County Tungsten Mining District, Boulder County, Colorado, USA

Dimensions: 9.5 cm x 7.5 cm

A sample of tungsten ore from the Conger Mine, consisting of back ferberite and white quartz, cut by tan silicified rocks typical of the vein casing.

Collected from the dumps on 22 July 2023; currently in the Polhemus collection, catalog # POL-MIN-2023-0181.

Dan A. Polhemus photo, 2023.

DF0-75GFerberite FeWO₄ , Quartz SiO₂

Conger Mine, Boulder County Tungsten Mining District, Boulder County, Colorado, USA

Dimensions: 8.0 cm x 4.0 cm

A sample of tungsten ore from the Conger Mine, consisting of inclusions of white quartz in a matrix of black ferberite.

Collected from the dumps on 22 July 2023; currently in the Polhemus collection, catalog # POL-MIN-2023-0179.

Dan A. Polhemus photo, 2023.

N2X-JV8Ferberite FeWO₄

Conger Mine, Boulder County Tungsten Mining District, Boulder County, Colorado, USA

Field of View: 1.35 mm

Blocky crystals of ferberite, the primary ore of tungsten at the Conger Mine.

Dan A. Polhemus photo, acquired using a Leica DMC 5400 digital camera linked to a Leica M-165C computerized microscope, with photo compositing using Leica Application Suite X AutoMontage software, and post-processing using Photoshop 8.0.

Collected from the dumps on 22 July 2023; currently in the Polhemus collection, catalog # POL-MIN-2023-0177.

Conger Mine ore chute, 22 July 2023

Conger Mine, Boulder County Tungsten Mining District, Boulder County, Colorado, USA

The old ore chute is the only structure remaining at the Conger Mine near Nederland, Colorado. This was formerly one of the largest tungsten mines in the United States, exploiting an extensive vein tungsten deposit.

Dan A. Polhemus photo, 2023.

8RM-QX5Chalcanthite CuSO₄·5H₂O

Blue Lizard Mine, Red Canyon Mining District, San Juan County, Utah, USA

Field of View: 2.60 mm

Small prismatic and tabular crystals of the pale blue cupric sulfate chalcanthite, which is common at the Blue Lizard Mine.

Dan A. Polhemus photo, acquired using a Leica DMC 5400 digital camera linked to a Leica M-165C computerized microscope, with photo compositing using Leica Application Suite X AutoMontage software, and post-processing using Photoshop 8.0.

Ex. Michael Shannon; currently in the Polhemus collection, catalog # POL-MIN-2020-0039.

JEL-3LXNatrozippeite Na₅(UO₂)₈(SO₄)₄O₅(OH)₃·12H₂O

Blue Lizard Mine, Red Canyon Mining District, San Juan County, Utah, USA

Field of View: 1.60 mm

Lumpy aggregates of natrozippeite, the sodium-dominant member of the zippeite group of uranyl sulfates, with intermixed with translucent pale blue chalcanthite which appears green due to the yellow natrozippeite beneath. This seems to be the most common member of the zippeite group at the Blue Lizard Mine.

Dan A. Polhemus photo, acquired using a Leica DMC 5400 digital camera linked to a Leica M-165C computerized microscope, with photo compositing using Leica Application Suite X AutoMontage software, and post-processing using Photoshop 8.0.

Ex. Michael Shannon; currently in the Polhemus collection, catalog # POL-MIN-2020-0008.

U2J-FAPSideronatrite Na₂Fe(SO₄)₂(OH)·3H₂O , Chalcanthite CuSO₄·5H₂O , Halotrichite FeAl₂(SO₄)₄·22H₂O

Blue Lizard Mine, Red Canyon Mining District, San Juan County, Utah, USA

Field of View: 2.00 mm

Yellow crystal aggregates of sideronatrite, a rare sodium-iron sulfate, on blue chalcanthite, with pale needles of halotrichite, from the Blue Lizard Mine.

Dan A. Polhemus photo, acquired using a Leica DMC 5400 digital camera linked to a Leica M-165C computerized microscope, with photo compositing using Leica Application Suite X AutoMontage software, and post-processing using Photoshop 8.0.

Ex. Michael Shannon; currently in the Polhemus collection, catalog # POL-MIN-2020-0033.

3PG-T22Plášilite Na(UO₂)(SO₄)(OH)·2H₂O

Blue Lizard Mine, Red Canyon Mining District, San Juan County, Utah, USA

Field of View: 0.82 mm

Tiny prismatic crystals of plasilite, a rare sodium uranyl sulfate, from the type locality at the Blue Lizard Mine. This is a former Jerry Baird specimen, with the identification based on his label, and comparison to other online photographs. The material fluoresces bright green under 365 nm long wave ultraviolet light. This was a difficult specimen to photograph.

Dan A. Polhemus photo, acquired using a Leica DMC 5400 digital camera linked to a Leica M-165C computerized microscope, with photo compositing using Leica Application Suite X AutoMontage software, and post-processing using Photoshop 8.0.

Ex. Jerry Baird thumbnail specimen, via Michael Shannon; currently in the Polhemus collection, catalog # POL-MIN-2022-0297.