September 18 to 21 Saturday – In Carson City, Sam wrote his mother, Jane Clemens, of the events at Lake Bigler:
When we got up in the morning, we found that the fire had made its way to within 4 or 5 steps of us on the South side. We looked like lava men, covered as we were with ashes, and begrimed with smoke. We were very black in the face, but we soon washed ourselves white again [MTL 1: 124].
Sam’s letter also reflected homesickness:

September 14–17 Tuesday – Sometime between these dates, Sam and John D. Kinney traveled to Lake Bigler (Tahoe), where they spent four days building a shack for a timber claim, then allowed their campfire to get away from them and were forced to flee from a wildland fire (not burning larger trees) [MTL 1: 126n3].

September 13 Friday ca. – Sam met John D. Kinney of Cincinnati (or day before) [MTL 1: 126n3].

September 12? Thursday – Sam arrived back in Carson City and wrote to Orion’s wife, Mary E. (Mollie) Clemens. Fragment survives:

September 10 Tuesday – Sam left Aurora. John D. Kinney (1840?-1878) arrived in Carson City from Cincinnati on this day or the next [MTL 1:126n2].

September 8 Sunday – Jane Lampton Clemens and Pamela A. Moffett wrote to Sam, letter not extant but mentioned in Twain’s Oct. 25 to Pamela [MTL 1: 129-136]. 

Horatio G. Phillips sold Sam fifty feet (shares) worth $10 each in claims of the Black Warrior Gold & Silver Mining Co. in Aurora, Esmeralda district [MTL 1: 134n4].

September, early – Sam traveled to Aurora, Nevada, in the Esmeralda mining district. In the late summer of 1861, both the Esmeralda and the Humboldt mining districts were the focus of gold fever. Sam would quickly acquire interests in both regions [Mack 126].

August 24 Saturday – Horatio G. Phillips (“Raish”) and Robert M. Howland (1838-1890), nephew of governor Nye, came down from Aurora to Carson City. They had several working mines and claims in the Esmeralda district. Sam met them shortly after their arrival, as they ate at Mrs. Murphy’s boarding house [Mack 132-3]. Sam later became partners in Aurora claims; Howland was to be that city’s marshal [MTB 176].

August 14 Wednesday – the pair arrived in Carson City, Nevada. The 20-day trip is recounted in Roughing It. The Clemens brothers boarded with Mrs. Margret Murphy, a “genial Irish-woman…a New York retainer of Governor Nye” [MTB 176]. Note: Murphy was “Bridget O’Flannagan” in RI [RI 1993, 613]. In 1860 the population of Carson City was a mere 701 souls and Virginia City 2,437; in 1861 Carson had doubled to 1,466; Virginia City had exploded to 12,704 [Mack’s Nevada: a History of the State, 1936].
Antonucci writes:

August 13 Tuesday – 19 th day out –
“…we crossed the great american desert – forty memorable miles of bottomless sand, into which the coach wheels sunk from six inches to a foot. We worked our passage most of the way across. that is to say, we got out and walked” [RI ch. 20].