There is indeed a Wheal Sophia on the shores of the Tamar a few hundred yards north of Moditonham Quay. A couple of pages are dedicated to it and the associated Wheal Fortune in my decaying copy of AKHJ's
Mines and Miners of Cornwall,Vol XIV, St.Austell to Saltash (pp62-64).
In 1846, "the finest mundic" was discovered on the Moditonham Estate in Botus Fleming on the shores of Kingsmill Lake. In 1851, an engine house, stack and 20" William West engine were installed on site and the shaft deepened to 20 fathoms. In the same year a lead lode was exploited in the North Adit. On 17 January 1852 the MJ carried an advertisement for the sale of the whole undertaking.
Close by on the Landulph side of the creek work began in spring 1851 on Wheal Fortune, which claimed to be an extension of the lodes of South Hooe.
In 1965 AKHJ could find no remaining trace of Wheal Fortune. However, in the same year, he noted the stack, shaft and burrow of Wheal Sophia intact in the grounds of a bungalow called (mistakenly, he said) Wheal Fortune, 200 yards N of Moditonham Quay. The adit, on the foreshore, had been examined by Sir Arthur Russell in 1950.
And, reader, I have seen Wheal Sophia's stack for myself- 1972 as I recall.