Mineralogy of Cornwall and Devon

IV.—Notes on the genus Homalonotus

“…rhenanus, Koch, 1 and IT. ornatus, Koch, 2 but as regards the obsolescence of the pygidial axis we see an approach to M. Icevicauda, Quenst., 3 though the headshield and outline of the pygidium are distinct in that species.…”

“…Salter's 3 earlier definition in 1865 makes no reference to the pygidial characters nor to the facial sutures, but it says that the genus is distinguished from Calymene, " its near ally," by its want of distinct trilobation, and goes on to state that "Homalonotus is elongate, convex, with steep sides and a very broad axis, scarcely distinguished from the pleura?. There are thirteen body-rings deeply grooved, and the fulcrum is close to the axis in most of the species.…”

“…Hall 3 has given a full description of the species, and we may quote his description of the course of the facial sutures: " The facial sutures take their origin on the lateral margins of the doublure in front of the genal angles and pass inward, parallel to the posterior margin of the cephalon, to the eye, thence forward with a broad curve inward to the anterior margin at the base of the prora, bending thence on to the epistomal doublure, meeting at its inferior margin. The branches of the facial suture are united on the upper surface of the prora by a straight transverse frontal suture, thus leaving a free median plate upon the epistoma, which is elongate-subtriangular in outline, attenuate at the apex, and recurved at the base, which forms the anterior portion of the prora."…”

Connoisseur's Choice: Tennantite, Tsumeb, Namibia

“…From the same locality crystals to 1.5 cm on edge with a sooty coating are included in the drawers of the Smithsonian's reference collection. Gregg and Lettsome (1858) as well as Collins (1969) also note the tennantite from Wheal Unity, Gwinear; Carn Brea mine, Illogan; Tresavean; East Relistian; and Huel Ryan. Collins (1969) lists specimens of chalcopyrite pseudomorphous after tennantite from the Levant and Crinnis mines.…”

“…Gregg and Lettsome (1858) as well as Collins (1969) also note the tennantite from Wheal Unity, Gwinear; Carn Brea mine, Illogan; Tresavean; East Relistian; and Huel Ryan. Collins (1969) lists specimens of chalcopyrite pseudomorphous after tennantite from the Levant and Crinnis mines. Crossing the Irish Sea to Ireland, the Gortdrum mine, Tipperary, County Tipperary, produced mercurian tennantite that was found in crystals to about 7 mm (Tindle 2008).…”