Here are the extracts from Dines (1956) that mention Ninnis:
South Lovell.-The exact position of this mine is not known. Cunnack (1885-1908) places it in a wood near Ninnis, half a mile S.W. of Seworgan, but the Ordnance map, at this place, bears the name South Wendron Mine. The plan (A.M. R 75 😎 shows a drainage adit extending from its portal 120 fms. N.E. and there changing direction to S.W. for 50 fms.; the latter part is called Combellack Adit. This suggests that the mine may be between Combellack Mine of the Wheal Lovell group and New Wheal Lovell (6-in. Corn. 76 N.E.), possibly in the rough ground east of Crowgey farm, the adit portal being in one of the valleys south of the farm. There is a small amount of development on four lodes, east of Combellack Adit, all coursing about E. 25° to 30° N. and underlying northwards. On the most southerly lode are Engine Shaft, 370 yds. E.N.E. of the adit portal, vertical to below Adit Level (12 fms.) and on the underlie to the 12-fm. Level, and Footway Shaft, 20 yds. E. of Engine Shaft, on the underlie to Adit Level only. Adit Level extends for 10 fms. N.E. and 35 fms. S.W. of Engine Shaft and the 12-fm. Level for 8 fms. N.E. and 35 fms. S.W. There is a block of stoping from surface to Adit Level for 20 fms. N.E. and 25 fms. S.W. of Engine Shaft and two tiny stopes on the 12-fm. Level. The next lode lies 15 fms. N. of the first and is opened up by crosscuts north from Adit Level at Engine Shaft and at 15 fms. W. of Engine Shaft, and by Perpendicular Shaft, 58 yds. W. of Engine Shaft. The only drive on this is Adit Level which extends 27 fms. N.E. of Perpendicular Shaft (to the crosscut from Engine Shaft) and 20 fms. S.W. At 12 fms. W. of Perpendicular Shaft a crosscut adit 25 fms. S. by W. joins Combellack Adit. From Adit Level 20 fms. N.E. of Perpendicular Shaft a crosscut 17 fms. N. by W. meets New Shaft on the third lode. This lode is nearly vertical and has been developed for 20 fms. N.E. of New Shaft at Adit Level and for 12 fms. S.W. at the 12-fm. Level. There is a stope from surface to Adit Level extending 22 fms. N.E. and 10 fms. S.W. of New Shaft and a small stope above the 12-fm. Level. The fourth or northern lode is proved in a crosscut 38 fms. N. of New Shaft at adit, but is only developed for 5 fms. N.E. In addition to a small yield from South Wheal Lovell in 1871, under the name Lovell Consols, the mine produced 81 tons of black tin from 1860 to 1868.
South Wendron.- Situated on the west side of the valley 1¾ miles E. by S. of Wendron (6-in. Corn. 76 N.E.) this mine is just south-east of Wheal Lovell. The plan (A.M. R 216D) shows Engine Shaft 20 yds. W. of the stream; its exact position cannot be located but it is believed to be 70 yds. N.E. of Ninnis. The shaft is an underlay 33° N. to the 40-fm. Level (below surface) and there are drives east at 20 fms., 25 fms., 30 fms., 31 fms. and 40 fms. from surface, none of which exceeds 6 fms. in length for the ore body is a pipe-like carbona of stanniferous granite, oval in section, measuring in plan 10 ft. by 20 to 60 ft.; it consists of cavernous quartz, chlorite, gilbertite, fluorspar and tourmaline with cassiterite, chalcopyrite and pyrite (Foster 1878a, p. 651). There was some opencast working to a depth of 5 fms. below surface and some very small stopes above the 25-fm. and 31-fm. levels and between the latter and the 40-fm. The only record of output is 7 tons of copper ore from 1875 to 1878.