Covellite inclusions in a Pink Fire Quartz from Brazil

Few years ago I had the chance to purchase in Bangkok (Thailand) a fine sample of the rare “Pink Fire” Quartz, selected from a small parcel. This material – reportedly from Minas Gerais region (Brazil) – has been seen for the first time in Tuscon (USA) in 2005 [1]Van Laer W.C. (n.d.) Pink Fire Quartz, Mindat.org and its inclusions identified by Raman as Covellite [2]Quinn E.P., McClure S.F. (2005) Covellite in Quartz, Gems & Gemology, vol. 41, No. 01, pp. 47 – 48, a copper sulfide (CuS) [3]Webmineral.com (n.d.) Covellite Mineral Data.

Here is below a picture of this 3.89 ct “Pink Fire” Quartz sample that shows some Covellite inclusions spread out a ventura thorough the gem.

Those crystallographically-oriented inclusions of Covellite appear dark green when seen under most angles (left side of the picture), but when observed at a right angle, those inclusions become miraculously hot pink (right side of the picture), creating an amazing and alive vivid pink flash when the sample is tilted back and forth. It’s like seeing a fire dancing within the gem, hence the apt trade name given to this unique type of quartz: “Pink Fire”.

When observed under a microscope, the thin hexagonal platelets appear dark green when viewed with transmitted light (light coming from below and so, going through the platelets – left part of the picture below) but appear vivid pink when the light reflects from their surfaces (light coming from above – right part of the picture), this due to a strong iridescent effect [4]Mineral Data Publishing (2001 – 2005) Covellite CuS, Handbook of Mineralogy (PDF).

This directional effect – that reminds of the Schiller effect sometimes seen in corundum – is truly a gemological curiosity, making this rare and interesting quartz a highly sought-after material for collectors.

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