This specimen presented a bit of a puzzle for us at first, because the old labels from the 1800s are so confused themselves about what to call this; but it turns out to be an exceptional specimen of this rare copper-bearing secondary mineral Chalcophyllite from the historic mining at Cornwall. Originally, because of the large crystals and blue saturated color, somebody thought that this was a large example of Liroconite but from Herrengrund (old German name), now Spania Dolina, with an unusually rich covering of large, teal green crystals. I showed it to an expert at Munich who confirmed that this is, in fact, Devilline from there of high quality - and yet, he was wrong as well! So it is NOT Liroconite from Herrengrund, nor Devilline from Herrengrund, but instead is a Chalcophyllite on classic Cornwall matrix. To put this to bed, we finally just had it analyzed and confirmed it is indeed Chalcophyllite by RAMAN (as shown) at the University of Arizona. Before MINDAT, Kay Robertson was considered the front of antique mineralogy knowledge, and she actually thought it might be a genuine Herrengrund liroconite, so it was a piece of pride in her notable suite from that locality. Tight clusters of teal-blue rosettes composed of 2 to 3 mm crystals cover the entire display surface Beautifully crystallized and colorful, this is one of the ultimate beautiful rarities that are hard to get in any quality beyond micros! The specimen surely dates to the heyday of mining here in the early or mid-1800s given the antique label (and it needed time to drift over to Germany and be mislabeled, as well). The history is fascinating because at that time, they could not tell the species apart anyways and perhaps Chalcophyllite had not even been described at the time this got to the famous dealer Maucher, who was himself usually very accurate with his labels. It is no wonder that Kay trusted his attribution and left this labeled as a Liroconite for decades in her collection. Previously from the Dr. Ing H. Maucher and Kay Robertson collections with labels. A historic specimen, that actually is a superb display piece, with a fine detective story!