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John A. Jaszczak's Photo Gallery

RLV-P1FMerelaniite Mo4Pb4VSbS15

08438250015697148546053.jpg
Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania

Largest Crystal Size: 0.7 mm

Cluster of cylindrical merelaniite whiskers with geometrially undulating diameter. This is a piece of the holotype specimen, occurring intermixed with graphite crystals in a crevice on an 11-cm long alabandite crystal.
Copyright: © John A. Jaszczak      Photo ID: 1002813     Uploaded by: John A. Jaszczak   View Count: 46   Approval status: Public galleries    Type: Photo - 4440 x 3176 pixels (14.1 Mpix)

TD6-QFWCopper Cu

06016690015692925512936.jpg
Seneca No. 2 shaft, Seneca Mine, Mohawk, Keweenaw Co., Michigan, USA

Dimensions: 16 inches x 14 inches x 6 inches
Weight: 16 lb

A large group of complex and distorted copper crystals measuring 16 x 14 x 6 inches and weighing 16 pounds. The very structural specimen consists of interwoven branches of copper crystals that have crystallized in large mass that formed in an altered zone in the Kearsarge amygdaloidal copper-bearing lode. The specimen is believed to have been collected in the 1940-1950s by a miner who recovered it from a "mud pocket" in the altered flow top. It is not known in who's mineral collection it was originally in but was found in a metal junk yard in Detroit, MI about 10 years ago by a collector and purchased for $40 (scrap metal price)-Tom Rosemeyer. John A. Jaszczak photo.
Copyright: © John A. Jaszczak      Photo ID: 1002137     Uploaded by: John A. Jaszczak   View Count: 20   Approval status: Public galleries    Type: Photo - 5616 x 3744 pixels (21.0 Mpix)

LNN-PF4Merelaniite Mo4Pb4VSbS15 , Zoisite Ca2Al3[Si2O7][SiO4]O(OH) , Graphite C , Calcite CaCO3

Multiple photos available
03115160015622043599516.jpg
Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania

Dimensions: 2.7 cm x 1.8 cm x 1.1 cm

Zoisite (var. Tanzanite) crystal on calcite and graphite matrix. The zoisite is included with numerous silvery cylindrical fibrous crystals of merelaniite. Some merelaniite is also in and on the calcite. Merelaniite inclusions in tanzanite is so far very rare, but at least one case documents is occurrence in a polished gemstone as well. See the brief article by Castillo, Augusto; Smith, Tyler; and Jaszczak, John A. (2018)
"Micro-World: Merelaniite inclusions in tanzanite" in Gems & Gemology 52(2) pp. 226-227.
Copyright: © John A. Jaszczak      Photo ID: 964751     Uploaded by: John A. Jaszczak   View Count: 25   Approval status: Public galleries    Type: Photo - 2000 x 3000 pixels (6.0 Mpix)

PV0-WELFluorapatite Ca5(PO4)3F , Graphite C

Multiple photos available
00593400015599535158097.jpg
Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania

Dimensions: 20 mm x 4.3 mm x 3.8 mm

Prismatic crystal with a complex termination, nicely showing the dichroism vwhen viewed along the c-axis as compared to perpendicular to the c-axis. The crystal also has a small cluster of tiny graphite crystals near the base (see child image). Another child image shows the dichroism when viewed through a polarizer.
Copyright: © John A. Jaszczak      Photo ID: 960163     Uploaded by: John A. Jaszczak   View Count: 75   Approval status: Public galleries    Type: Photo - 3000 x 2260 pixels (6.8 Mpix)

3M1-3D8Fluorapatite Ca5(PO4)3F

02204670015594008219736.jpg
Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania

Dimensions: 4 mm x 5 mm x 8.5 mm

Strongly dichroic fluorapatite crystal from the tanzanite gem mines near Merelani, Tanzania.
The central image is taken without a polarizer, whereas the left and right images are taken through a polarizer. In the leftmost image, the electric field is aligned perpendicular to the crystal's vertically-aligned c-axis, and in the rightmost image, the electric field is aligned parallel to the vertically-aligned c-axis of the crystal. Visible in the central image is an interesting line that runs up the prism face, along the pyramid and pinacoid, and back down another prism fave. The line seems to correspond to a small displacement between two sections of the crystal. John Rakovan collection. Ex. Kilimanjaro Gemstones.

Mindat.org Photo of the Day - 9th Jun 2019
Copyright: © John A. Jaszczak      Photo ID: 959089     Uploaded by: John A. Jaszczak   View Count: 510   Approval status: Public galleries    Type: Photo - 5500 x 2314 pixels (12.7 Mpix)

CNM-NJACopper Cu , Prehnite Ca2Al2Si3O10(OH)2

08254610015560680739685.jpg
St. Clair Mine, Phoenix, Keweenaw Co., Michigan, USA

Largest Crystal Size: 1.05 mm

A "fluted" native copper crystal 1.05 long on a matrix of crystallized prehnite. For lack of a more refined crystallographic term I have used fluted for twinning shown in the micro crystal. The St Clair mine is about one half mile northeast of the Phoenix mine and mined a narrow fissure vein that produced about one million pounds of copper from 1865-1885. On 20 May 2018 Yalmer F. Primeau and I collected the mine
dump and recovered a number of the fluted crystals along with copper needles that are shown in Photo #929542 (QGQ-GVN).-Tom Rosemeyer (John A. Jaszczak photomicrograph).
Copyright: © John A. Jaszczak      Photo ID: 951541     Uploaded by: John A. Jaszczak   View Count: 22   Approval status: Public galleries    Type: Photo - 1500 x 2256 pixels (3.4 Mpix)

1ET-HC4Merelaniite Mo4Pb4VSbS15 , Graphite C

07192130015534737535722.jpg
Merelani Hills, Lelatema Mts, Simanjiro District, Manyara Region, Tanzania

Largest Crystal Size: 0.55 mm

Whiskers of silvery merelaniite with minor associated graphite. The longest whiskers are about 0.55 mm long. This holotype material was originally in a crevice on an 11-cm long alabandite crystal.
Copyright: © John A. Jaszczak      Photo ID: 946241     Uploaded by: John A. Jaszczak   View Count: 39   Approval status: Public galleries    Type: Photo - 1250 x 841 pixels (1.1 Mpix)

QGQ-GVNCopper Cu , Prehnite Ca2Al2Si3O10(OH)2

03641270015464880909697.jpg
St. Clair Mine, Phoenix, Keweenaw Co., Michigan, USA

Largest Crystal Size: 1.28 mm

Native copper "needles" up to ~1.3 mm long (crystal on the right) on a matrix of crystallized prehnite. For lack of a more refined crystallographic term I have used "needles" for the unusual copper crystallization. The St Clair mine is located about a half mile northeast of the better known Phoenix mine and from 1865-1885 mined a narrow fissure vein that produced about one million pounds of copper. In mid-May 2018 Yalmer F. Primeau and myself collected the mine dump and recovered a number of micro crystals of copper that showed an unusual and rare form for the Michigan Copper Country. -Tom Rosemeyer. (John A. Jaszczak photomicrograph.)
Copyright: © John A. Jaszczak      Photo ID: 929542     Uploaded by: John A. Jaszczak   View Count: 47   Approval status: Public galleries    Type: Photo - 5184 x 3456 pixels (17.9 Mpix)

QDJ-WTRTitanite CaTi(SiO4)O , Chamosite (Fe2+,Mg,Al,Fe3+)6(Si,Al)4O10(OH,O)8

01689720015462733267525.jpg
Ojibway Mine, Ojibway, Keweenaw Co., Michigan, USA

Largest Crystal Size: .47 mm

A gemmy 0.47 mm crystal of titanite perched on a substrate of crystallized botryoidal chamosite. The crystals were contained in a chunk of brecciated amygdaloidal copper-bearing Kearsarge lode basalt. The specimen was collected at the Ojibway mine, #1 shaft, Keweenaw County, Michigan in July 2018 by Tom Rosemeyer. The late stage calcite filling cementing the flow top was removed with a dilute aqueous solution of sulfamic acid exposing the delicate crystals. Follow up Raman spectroscopy and SEM work by John A. Jaszczak at Michigan Tech gave tentative identification of the species. This is the first recorded discovery of euhedral titanite crystlals in the Michigan Copper Country-Tom Rosemeyer. (Photomicrograph by John A. Jaszczak)
Copyright: © John A. Jaszczak      Photo ID: 929222     Uploaded by: John A. Jaszczak   View Count: 52   Approval status: Public galleries    Type: Photo - 5184 x 3456 pixels (17.9 Mpix)

AYR-2XTGold Au , Quartz SiO2

01819450015239303512294.jpg
Itogon mine, Baguio District, Benguet Province, Cordillera Administrative Region, Luzon, Philippines

Field of View: 2.9 mm

"Delicate ribbons of gold associated with crystallized quartz. The specimen was mined in 1935 on the Sesame vein, Itogan mine at Baguio on the island of Luzon. The father of a good friend of mine who lives in Ouray, Colorado was mine manager at the time and collected the high grade gold specimens which I was able to acquire. He departed just before the Japanese Imperial Army invaded the Philippines on 8 December 1941." -Tom Rosemeyer. Tom Rosemeyer specimen. John A. Jaszczak photomicrograph.
Copyright: © John A. Jaszczak      Photo ID: 885663     Uploaded by: John A. Jaszczak   View Count: 154   Approval status: Public galleries    Type: Photo - 5184 x 3456 pixels (17.9 Mpix)
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