BOLTWOODITE (Hydrated Potassium Uranyl Silicate Hydroxide)

BOLTWOODITE specimens:
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BOLTWOODITE specimen btw-1
$ 225.00

Dims: 3.2 x 2.7 x 2.0" (8.9 x 6.1 x 5.1 cm)

Wt: 9.3 oz. (264.6 g)

Arandis, southwest Africa

Several clusters of compact, fibrous, radiating Boltwoodite crystals rest on the dull brown calcareous host rock of this specimen. Though appearing incomplete, these clusters do not show any fresh or human-induced damage. The crystals that comprise them do not exceed 0.3" (8 mm) and are so fine and compacted that study of their form is impossible. All have a pale yellow coloration and a dull waxy luster that appears silky when compacted into clusters, and are opaque. They rest in small cavities in the host rock that are lined with a black crust (uraninite, I would guess) that mostly covers a bed of tiny calcite scalenohedrons. The host rock that holds these is generally dull in luster and has a color ranging from cream to moderately pale brown to black.

btw-1 ($225.00)

Arandis, southwest Africa

BOLTWOODITE specimen btw-2
$ 30.00

Dims: 2.5 x 2.1 x 1.6" (6.4 x 5.3 x 4.1 cm)

Wt: 4.57 oz. (129.7 g)

New Method Mine, San Bernardino County, California, U.S.A.

Several sprays of tiny, acicular Boltwoodite blades rest on the limestone host rock of this specimen. The crystals in the clusters are very small, not exceeding 0.1" (3 mm) in length or 1 mm in thickness. All appear to be in very good condition, showing little or no damage, and though they are too small for me to effectively study with a loupe, I think that the crystals have a moderately good monoclinic form their faces show a good pearly luster, at least. They have the standard yellow coloration of Boltwoodite and are so small that they are easily translucent. The sprays rest among a druse of almost microscopic calcite crystals that coat a small portion of the limestone host rock.

btw-2 ($ 30.00)

New Method Mine, San Bernardino County, California, U.S.A.

BOLTWOODITE specimen btw-3
$ 50.00

Dims: 3.2 x 3.0 x 1.5" (8.1 x 7.6 x 3.8 cm)

Wt: 9.03 oz. (256.2 g)

New Method Mine, San Bernardino County, California, U.S.A.

The metamorphic host rock of this specimen is partly covered with several thin Boltwoodite crusts. These crusts are made of massive material, and show no detectable crystal form or crystalline tendencies. The Boltwoodite has a deep yellow coloration and a dull, waxy luster, and is likely translucent at its present thickness. The host rock contains a large amount of quartzite and a few thin layers of a black, crystalline material that I cannot identify.

btw-3 ($ 50.00)

New Method Mine, San Bernardino County, California, U.S.A.

BOLTWOODITE specimen btw-4
$ 55.00

Dims: 1.2 x 1.2 x 1.2" (3.0 x 3.0 x 3.0 cm)

Wt: 22.2 g

Rossing Mine, Swakopmund District, Namibia

Several tiny, intergrown Boltwoodite clusters rest in a hollow in the shale host of this specimen. These clusters are in moderately good condition, as several are damaged and incomplete, and reach maximum diameters of 0.1" (3 mm). The intact clusters are intergrown to form a botryoidal "crust", and the broken ones show the compact, radial nature of the crystals therein. These broken areas have a deep yellow color and a pearly luster, whereas intact surfaces are colored a much darker, nearly orange color and show a dull, almost silky luster. They are accompanied by a crust of several tiny, intergrown calcites that are brown in color.

btw-4 ($ 55.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-5
$ 35.00

Dims: 1,0 x 0.9 x 0.8" (2.5 x 2.3 x 2.0 cm)

Wt: 14.9 g w/ specimen box

Rossing Mine, Swakopmund District, Namibia

Two clusters of radiating Boltwoodite needles rest in a hollow in the brown host rock of this piece. One of these clusters is incomplete due to its position at the edge of the piece, but the other is intact and in excellent condition. The needles therein do not exceed 0.1" (3 mm) in length and likely have very good monoclinic form. Their deep yellow coloration and pearly luster are standard for their species, and individual crystals are generally translucent. The host rock on which they rest appears to be made of siderite or calcite, or both.

btw-5 ($ 35.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-6
$ 45.00

Dims: 1.2 x 0.8 x 0.3" (3.0 x 2.0 x 0.8 cm)

Wt: 10.8 g w/ specimen box

Rossing Mine, Swakopmund District, Namibia

This thumbnail specimen consists of several clusters of radiating Boltwoodite needles that rest on a base of what appears to be goethite and calcite. The needles do not exceed 0.1" (3 mm) in length and are generally in good condition, though several clusters are damaged or crushed, showing their radial habit. All have the bright, maize-yellow coloration of their species and a pearly luster, and are generally translucent.

btw-6 ($ 45.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-7
$ 65.00

Dims: 1.3 x 1.0 x 0.9" (3.3 x 2.5 x 2.3 cm)

Wt: 15.7 g

Rossing Mine, Swakopmund District, Namibia

Several sprays of tiny Boltwoodite needles rest on the calcite/siderite base of this piece. Though a few of these clusters are damaged, most are in excellent condition. The needles therein are a bit too small to effectively study with a loupe, but they appear to have good monoclinic form. All have the "maize-yellow" color and pearly luster that are common for this specie, and are generally translucent.

btw-7 ($ 65.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-8
$ 35.00

Dims: 1.6 x 0.7 x 0.6" (4.1 x 1.8 x 1.5 cm)

Wt: 10.3 g)

Rossing Mine, Swakopmund District, Namibia

This thumbnail specimen consists of 3 or 4 small clusters of radiating Boltwoodite needles that rest on a calcite or siderite base. One of the clusters is much larger and more full than the others, containing hundreds of crystals- the smaller ones each contain less than 10 crystals. The crystals are in very good condition and are almost too small for one to effectively study their monoclinic form. Their deep yellow coloration and dull pearly luster are standard for material from this locality. They rest on what appears to be a very thin goethite crust that covers the base.

btw-8 ($ 35.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-9
$ 135.00

Dims: 2.0 x 1.2 x 1.1" (5.0 x 3.1 x 2.7 cm)

Wt: 1.6 oz. (44 g)

Rossing Mine, Swakopmund District, Namibia

A single cluster of radiating Boltwoodite needles rests on the sandstone base of this hand specimen. The cluster measures 0.6 x 0.4 x 0.2" (1.5 x 1.0 x 0.5 cm) and is in excellent condition, showing very little damage. Its crystals are quite fine, but likely have a good monoclinic form. Their deep yellow color and silky to pearly luster are standard. The cluster rests on a bed of tiny calcite dogtooth crystals. Like all uranium-bearing minerals, this piece emits radiation that is easily detected with personal radiac equipment or a Geiger-muller counter.

btw-9 ($135.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-10
$ 135.00

Dims: 1.8 x 0.8 x 0.7" (4.6 x 2.0 x 1.7 cm)

Wt: 15 g

Rossing Mine, Swakopmund District, Namibia

A single spray of radiating Boltwoodite crystals rest on the sandstone base of this hand specimen. The crystals that make up the spray do not exceed 0.2" (4 mm) in length and are generally in good condition, though the spray does show some light damage in one area. The crystals are too fine for easy study, but likely have good monoclinic form. Their deep yellow color and pearly luster are standard. They rest on a bed of siderite or calcite that is coated with what could be a thin layer of goethite- I doubt that it is uraninite, in any case. Radiation from this piece is readily detected on most standard radiation meters and geiger counters.

btw-10 ($135.00)

Rossing Mine, Swakopmund District, Namibia

BOLTWOODITE specimen btw-11
$ 30.00

Dims: 1.3 x 0.9 x 0.8" (3.3 x 2.2 x 2.0 cm)

Wt: 12 g

Rossing Mine, Swakopmund District, Namibia

A few small sprays of tiny, radiating Boltwoodite crystals rest on the calcareous base of this thumbnail piece. Two of these sprays are larger than the rest, measuring 0.1" (3 mm) and 0.2" (5 mm) in diameter, respectively, and are in excellent condition. The others are either much smaller or are damaged. All contain fine, monoclinic needles that have the standard yellow color and silky luster. They rest on a bed of dogtooth calcite crystals that coat a base of calcite and shale. A standard Geiger-muller radiation counter will react readily to this piece.

btw-11 ($ 30.00)

Rossing Mine, Swakopmund District, Namibia

THE MINERAL BOLTWOODITE

PHYSICAL CHARACTERISTICS: