Trip Report: Read...
A well done site with lots of great pictures covering the 2004 Geo-Adventure Tour from a member’s perspective.

New Pictures and website: view...
One of the members of the 2004 Geo-Adventure Tour has put an excellent set of pictures up.....

Trip Report
2004 Geo-Adventure Tour to Greenland read...
The trip was a resounding success (in spite of lousy weather). Read the details in the Trip Report section and get ready for the next tour in August of 2005. Sign up now, space is limited..

World’s Finest Tugtupite
Specimen - view...
A major specimen was recovered from the gem tugtupite mines this summer. It is probably the largest and finest piece ever recovered from these mines (which are rapidly being depleted). Check it out - this may be the last opportunity to add a truly world-class specimen to your collection

 
Nuummite

Nuummite is a gemstone formed from a mixture of two minerals from the orthoamphibole group: anthophyllite and gedrite. The name nuummite is derived from the Municipality of Nuuk, where the stone was discovered in 1982.  It has since been found in several localities in the outer part of the Godthabsfjord near Nuuk.

Geologically speaking, nuummite is of volcanic origin and was formed about 3 billion years ago.  Subsequent influences on the rock (metamorphism) have given rise to the striking mixture of crystals which gives nuummite its unique appearance.  Rocks resembling nuummite are also found in a few minor occurrences in the USA, but it is only in the Greenland type that coloration is developed well enough for the stone to be suitable for gemstones.

Composition

In nuummite, the two orthoamphibole, anthophyllite (Mg,Fe)₇Si₈O₂₂(OH)₂ and gedrite (Mg,Fe)₅Al₂(Al,Si)₈O₂₂(OH)₂, both with a hardness of 5 to 5.6, constitute a mixture of elongated crystals, often in sheaf-like groups. In the transition between the individual crystals (and especially the thin ones), an optical effect is created causing a special “inner” golden brown glow.  This effect is also called iridescence, and is especially distinct on polished surfaces.  The result is that the crystals appear as bright lamellae, almost like flames in a fire.  The colors vary somewhat between reddish, greenish, and bluish hues, sometimes even within the same lamella. Between the bright lamellae, the color is dark brown to black.

Nuummite is generally easy to polish, even though, in certain qualities of stones with many parallel crystals, it can be difficult to avoid holes and cracks. The usual shape is cabochon, but other convex finishes also produce pleasing results. In larger pieces it is possible to retain most of the colors of the iridescence, so that one end of the cabochon has a golden hue while the opposite end has a bluish tone.  Nuummite is well suited to mounting in both gold and silver.

JSG har Nuummit på lager

   Nuummit I skiver        Nuummit Klumper på op til ca. 3 til 7 kg.

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Senest opdateret: 10. January 2005