Cobaltian calcite at its best has the most stunning color in the mineral world, to my taste (and Jack shares it, as he pursued these aggressively and they were over-represented in his collection!) This specimen was among Jack's top 3 of 9 of these gorgeous cobaltian calcites he had at the peak size of the collection, and I begged him for just one for myself back in the early 2000s as I was strongly collecting calcites. This was traded out to me at that time, and has been in my own calcite collection. I collected calcite since the mid-1980s, and I had always dreamed of owning a good one of these! I have since mostly deaccessioned my calcites as I graded my old collection into Chinese-specific minerals the last 20 years - but I KEPT this piece all this time. His suite of these was beautiful, and as a color aficionado they were among his favorite toys - for obvious reasons when you look at these photos. This piece features a proud, upright 5.5 cm-tall crystal at the edge of a mountainous quartz matrix, and with a bit of dark green kolwezite as accent to the side. Jack bought this directly from Ken Roberts in the early 1990s, as Ken had a number of them and was at the time located in the San Francisco Bay Area near Jack. I always felt that the combination of color, crystal size and placement, and the interesting matrix that displays the crystal made this a very impactful piece, and I have had pleasure to keep it in what remains of my childhood and early calcite collection, all these years. For those new to seeing these, all I can say is that in person, the color is surreal and you would assume it to be the fake product of a chemistry experiment - there is no color in minerals like these at their best! Modern material from Morocco is also beautiful, but different. These are still the standard, and I am not aware of many out in the public at this late date after nearly 30 years since they were found.

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