#gersdorffite

[mineralsandsomerocks]

Native Silver (tarnished yellow) overgrown by Nickeline (pink) and Rammelsbergite (whitish grey rim on Nickeline) and Gersdorffite (light grey, euhedral crystals) and partially replaced by intergrown Acanthite (dull, scratched grey) and Stephanite (slightly lighter, "cleaner" grey)

Locality: Easter-Duffy Deposit, Greater Slave Lake, Northwest Territories, Canada

Plane Polarized Reflected Light, 50X Magnification

Have not had time to take new pictures of my newer rocks, as I have been super busy working on my MSc, so I thought I would upload some reflected light images from my thesis! If it seems like these are something folks want to see, I have loads more where this came from. Plus tumblr has a lack of reflected light microscopy images anyways. Feel free to reach out if you have any questions about this stuff!

[sarahmagdalena-blog]

Nickeline, Gersdorffite, Annabergite, Calcite and Fluorite.

[mineralia]

Gersdorffite from Morocco

[mineralsandsomerocks]

Nickeline (pink/peach) and Maucherite (pinkish grey) with a rim of Gersdorffite (bluish grey) overgrown by intergrown Parkerite (light grey, twinning) and Hauchecornite (dull pink), then overgrown by Matildite (darker grey, rough texture).

Locality: Easter-Duffy Deposit, East Arm Region, Greater Slave Lake, NWT, Canada

Reflected Plane Polarized Light, 200X Magnification

Quick laundry list of minerals most people will have never heard of!

[comfycat3]

taking some notes for my own study later

Nickeline: NiAs, hexagonal, pale copper red

Maucherite: Ni11As8, tetragonal, warm silverly white turning darker grey when oxidised

Gersdorffite: NiAsS, isometric, grey to white

Parkerite: Ni3(Bi,Pb)2S2, monoclinic, pale bronze

Hauchecornite: Ni9BiSbS8, tetragonal, bronzy yellow

Matildite: AgBiS2, trigonal, silvery black or grey

Ni-Co-Ag deposits or five-element (Ni-Co-As-Ag-Bi) vein type deposits, the name is not really that accurate as it often has Fe, U, but we persist. It tends be exist in continental crust where extensional tectonics occur.

Ore precipitation theories

Natural Fracking - This is the current leading theory. Liberation of hydrocarbons during the break up of rocks near hydrothermal systems. Mixing of hydrocarbonates and metal rich hydrothermal fluids precipitate ore (Markl, Burisch, Neumann, 2016).

Iron oxidation - Correlates pyrite abundance with mineralisation (Ondrus, et al., 2003)

Fluid mixing - Fluids of different pH mixing. Ore fluids are shown to be alkaline, and the proposed precipitation is caused by decreasing pH. (Staude, et al., 2012)

Boiling... or Cooling? - High temperatures in the crust mobilise saline and ~400°C fluids, and scavenge Ni-Co-Ag from surrounding rock. The deposition mechanism is reduction and boiling. (Kissin, 1992)

im tired, back to porphyry work. i may or may not come back with more <3

Nickeline (pink/peach) and Maucherite (pinkish grey) with a rim of Gersdorffite (bluish grey) overgrown by intergrown Parkerite (light grey, twinning) and Hauchecornite (dull pink), then overgrown by Matildite (darker grey, rough texture).

Locality: Easter-Duffy Deposit, East Arm Region, Greater Slave Lake, NWT, Canada

Reflected Plane Polarized Light, 200X Magnification

Quick laundry list of minerals most people will have never heard of!