Smaragdite (Verdi di Corsica)
Mineralogists are developing a distinct species for this stone. It has feldspar for its cement, and green diallage for its markings. It exhibits interesting varieties that arise from one single origin. It is found on the Island of Corsica, precisely on the mountain of S. Pietro di Rostino near Orezza. It is not worked much because it is very hard, but it is of an extraordinary beauty.
700. (167.1) Verde di Corsica semplice. Grey blue ground with markings of a very vivid grass green. In Rome I have only seen it as some slabs in the first chapel to the left of the church of S. Andrea della Valle. (Very rare).
701. (167.2) Verde di Corsica mandolato. Whitish ground divided into fragments and with some green veins. (Rare).
702. (167.3) Verde plasma. Another type of verde di Corsica with a white ground, that is almost invisible because it is covered with an exquisite green similar to plasma. A very beautiful urn can be seen under the last altar to the right in the church of S. Antonio de' Portoghesi. (Very rare).
973. (Suppl.23.1) Verde di Corsica. Deep green ground with white markings. (Rare).