Quartz oscillator using a large irregular (natural) piece of quartz crystal for maximum Q?
Since it seems that you are essentially attempting to create your own crystal from very raw materials (a chunk of quartz), what would probably be most useful would be to read about the early pioneers of the electronic quartz crystal industry.  One excellent source is Christopher McGahey's PhD dissertation on the history of the industry.  The most useful thing in it for you will be the footnotes and bibliography which will point you to the original sources in which inventors in the late 19th and early 20th centuries described their early experiments with quartz crystals.  

Also useful will be looking at patents such as US Patent 2,212,845 which was filed in 1918 and describes an early oscillator design and US Patent 1,414,370 which describes how to make a suitable crystal.