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Identity HelpGraphite? (Norway)

29th Feb 2020 10:47 UTCGianna Ragagnin

Hi,

I found this rock at the dump pile from the E12 tunnel excavation at the Norwegian-Swedish border near Umbukta (Mo i Rana municipality, Norway). Bedrocks, as listed by Geological Survey of Norway, are micaschist/zoisite-calc-micaschists, with quartz veins, garnet and kyanite bearing, or with brown calcite in quartz.

This rock has a big brown calcite crystal, with black, metallic flakes in it, ca 1 mm thick and 1,2 cm wide.

Steel can easily scratch it, but not my nails. Streak is black, also on paper.

I tentatively identified it as graphite bc of streak and crystal habit, but this mineral is not listed for this locality/adiacent ones. It's also harder than 1-2 (on the other hand, we had a chunk of graphite in my Mineralogy class which also was harder than 1-2).

I welcome a more qualified opinion than mine, eventually from someone who knows the area.

7th Mar 2021 16:48 UTCKnut Eldjarn 🌟 Manager

If the mineral is soft enough to make a black streak on paper, it could still be graphite. There are many localities with graphite in Norway not listed in Mindat.

7th Mar 2021 18:56 UTCPaul Brandes 🌟 Manager

I tend to agree with graphite based on what you've told us, Gianna.

I can't tell in the photo but if it had a blueish cast, it could also be molybdenite.

12th Mar 2021 14:21 UTCGregg Little 🌟

Wouldn't the streak colour rule out molybdenite. Of course if the streak was improperly performed then that would be misleading, eh?

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