A few months back I decided to starting making records of most of my knapping attempts, recording the dimensions of the starting spall, the time spent working on the piece, and the dimensions of the finished pieces. Compiled here are some preliminary results from my quartzite knapping. All of the quartzite used was derived from cobbles collected in central Virginia, except for two pieces of ferruginous quartzite from somewhere in the mountains. All dimensions are given in millimeters, time is given in minutes:
Success rate: 47 spalls resulted in 29 finished points, 62% success rate. Pieces were pushed only to where I felt I had reached the limit of my ability and the limit of the ability of the stone. (I was working inside my comfort zone).
Total spent on completed pieces: 609 minutes.
Avg. time per finished piece: 21
Total time on failures: 221
Avg. time per failure: 12.3
Considering total time and 29 finished pieces, 28.6 minutes of knapping time needed per point.
L: Range 51.8 - 108, avg. 79.3
W: Range 27 - 68, avg. 43.2
T: Range 8 - 13, avg. 10.4
w/t ratio: Range 3.2 - 5.6, avg. 4.1
Spall data. No significant differnce in dimensions was found between spalls that produced a point versus those that failed, so data is for all 47 spalls. Only averages are given:
In phase two an attempt will be made to push all quartzite bifaces to 10mm or thinner, regardless of other dimensions. (Trying to work beyond my comfort zone.)