John A. Jaszczak's Photo Gallery
CL4-F88Merelaniite Mo4Pb4VSbS15 , Graphite C , Prehnite Ca2Al2Si3O10(OH)2 , Chabazite, Zoisite (Var: Tanzanite) (CaCa)(AlAlAl)O[Si2O7][SiO4](OH)
Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, TanzaniaLargest Crystal Size: 0.8 mm
Silvery cylindrical whisker of merelaniite in a small space between blades of zoisite (tanzanite), and associated with flakes of graphite, pseudocubic chabazite (top left out of focus) and prehnite coating the zoisite. This crevice also hosted several other merelanite whiskers with undulating diameters along the whisker axis.
AR8-NC1Graphite C , Zoisite (CaCa)(AlAlAl)O[Si2O7][SiO4](OH)
Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, TanzaniaLargest Crystal Size: 0.15 mm
Symmetrical graphite crystal (0.15-mm on edge) included in a pale lavender-colored zoisite (tanzanite) crystal from Merelani Hills. It is quite rare to find graphite crystals that are undamaged and symmetrical. The image was taken using a stack of 15 images combined using Helicon Focus. (20-mm Zuiko lens, bellows and extension tubes).
NLX-GYHGraphite C
Malyn, Korosten Raion, Zhytomyr Oblast, UkraineLargest Crystal Size: 1.5 cm
Orbicular graphite (orbs up to 1.5 cm) in granite from the Malyn granite quarry #3, Korosten gabbro-anorthosite -- rapakivi-granite pluton.
M9R-YG5Alabandite MnS , Sphalerite ZnS , Graphite C
Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, TanzaniaLargest Crystal Size: 9.5 mm
A prominent, tabular black alabandite crystal (9.5 mm on edge) with octahedral faces that is spinel-law twinned is associated with orange-red sphalerite and perhaps wurtzite, along with a few other octahedral alabandite crystals, minor graphite crystals, and tiny white tremolite(?) fibers. Some of the sphalerite crystals show a bright orange color due to internal reflection of the light. (Collection of the A. E. Seaman Mineral Museum; ex Simon Harrison.)
612-VHXMolybdenite MoS2 , Sodalite Na4(Si3Al3)O12Cl
Poudrette quarry, Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, CanadaLargest Crystal Size: 0.5 mm
Spheroidal molybdenite in sodalite from the "sodalite xenolith" at the southwest corner of the Poudrett Quarry. Molybdenite spheres like these show a radial texture when broken. The sodalite fluoresces bright orange in long- and short-wave ultraviolet light. Collected in April 1991 by R. Peter Richards. (This image is from a scanned Ektachrome 64T 35-mm transparency.)
F0K-VLLCopper Cu , Quartz SiO2 , Epidote (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Ahmeek No. 1 Shaft, Ahmeek Mine, Ahmeek, Allouez Township, Keweenaw County, Michigan, USALargest Crystal Size: 4 mm
A delicate "nest" of copper wires in a vug of crystallized epidote and quartz. The copper wires were exposed by leaching the late-stage calcite with a dilute aqueous solution of sulfamic acid. The specimen was collected on 26 June 2021 by Tom Rosemeyer at the Ahmeek #1 shaft that mined the copper-bearing amygdaloidal Kearsarge lode. The nest of wires was a surprise as they are quite rare in the Kearsarge lode, and is a welcome addition to my collection-Tom Rosemeyer. (John A. Jaszczak photo.)
P9T-7YPAnatase TiO2 , Quartz SiO2
Allouez Conglomerate Mine, Allouez, Allouez Township, Keweenaw County, Michigan, USALargest Crystal Size: 0.12 mm
Tiny thin tabular yellow crystals of anatase associated with quartz in a leached vug in a clast of Allouez Conglomerate. Anatase is very rare in the Michigan Copper District and has been found at only two localities to date; those being the Allouez Conglomerate mine and the Manganese mine near Copper Harbor, Keweenaw County. The anatase crystals appear to be been formed in the early stages of alteration in the Portage Lake Volcanics and not directly associated wit the main "Native Copper Mineralization Event." The specimen shown was collected on 15 May 2021 by Tom Rosemeyer and resides in his collection. John A. Jaszczak photo. Comments are invited on the timing of the crystallization of the anatase. - Tom Rosemeyer
MAU-5MRCopper Cu
Copper Falls Mine, Copper Falls, Eagle Harbor, Keweenaw County, Michigan, USADimensions: 2.4 cm x 2.2 cm x 4.5 cm
Largest Crystal Size: 4 mm
The Copper Falls Mine was one of the early producers in the Michigan Copper District and mined a number of copper-bearing fissure veins. Early production from the veins produced many beautiful crystallized copper specimens. Early on, supervisors and miners learned the value of the specimens, which now grace museums and private collections. The specimen shown is a rare and unique specimen that was probably collected early in the mining operations. The specimen shows stacked octahedrons in parallel growth. Octahedral copper crystals are rare in the Michigan Copper District, and this is the first specimen I have seen like this in my 63 years of collecting the Copper Country. The stacked octahedrons attain a length of 1.6 cm and individual octahedrons range up to 4 mm on edge. Tom Rosemeyer collection. John A. Jaszczak photo.
0P2-4NDCopper Cu , Silver Ag
Isle Royal No. 5 shaft, Isle Royal Mines, Portage Township, Houghton County, Michigan, USADimensions: 10.4 cm x 11.2 cm x 14.8 cm
Again I use a non-scientific descriptive term of "ropy copper" to describe this unique and rare copper/silver specimen from the Keweenaw Peninsula of Michigan. The specimen was collected at the No 5 shaft of the Isle Royale mine in the summer of 2010 when the mine dump was being crushed for road aggregate. The chunk of altered and crumbly copper-bearing amygdaloidal basalt was recovered with the aid of a metal detector, and the enclosing rock was removed with a high-pressure power washer that revealed the ropes of copper along with splotches of silver that partially coat the specimen. The copper was coated with grungy, ugly copper carbonates and oxides that were removed by leaching in an aqueous solution of dilute muriatic acid. The copper, but not the silver, has a dark brown patina that is due to the small amount of arsenic that is alloyed with the copper and called "arsenical copper." The copper ropes in this specimen have a roughly square cross-section and range from 3-6 mm on edge. The longest rope would be 18 cm long if unbent and stretched out! Specimens with this type of crystallization were mainly found in the Osceola lode associated with crystallized prehnite. Several of this type were in the original John T. Reeder collection and are now on display in the A. E. Seaman Mineral Museum at Michigan Technological University in Houghton, Michigan. --Tom Rosemeyer
FKW-M9NCopper Cu
Phoenix Mine, Phoenix, Houghton Township, Keweenaw County, Michigan, USADimensions: 1.5 cm x 1.4 cm x 3.6 cm
This unique specimen of crystallized copper was collected in the Keweenaw on 13 August 2020. About 10 years ago, dump rock was removed from the mine and transported to the nearby Phoenix Farm Road to repair an existing ATV trail. While metal detecting the area this summer, the totally calcite-encased copper specimen was recovered from a ditch along the trail. No copper was visible, but its ring on the metal detector was a very good indication of it's hidden presence under the substrate. A bath in a sulfamic acid solution partially exposed the crystallization that was present. The copper was still partially covered with a grungy coating of microcline, which was removed with another bath in hydrofluoric acid. Now the true beauty and rare crystallization of the piece was completely exposed. The specimen is roughly triangular in shape, a floater with no points of attachment to the enclosing matrix, and is composed of stacked hoppered cubic copper crystals showing relatively sharp cube edges and corners. A crystal of this size and perfection is a once in a lifetime find, and shows that there are still surprises to be discovered in the Keweenaw --Tom Rosemeyer. (photo by John A. Jaszczak)