First of all, my wife and I want to thank you for encouraging us to make the trip to Navajun. It was a great experience. We were extremely fortunate to have good weather. We arrived on Nov. 19th and went into the mine on Nov. 20th. The weather was bright and sunny and about 68 degrees F. The next day it turned cold and rainy, so we just made it in time.
As you said, it was the thrill of a lifetime to see the pyrite crystals all over the walls of the excavation site. We spent one morning digging like kids in a candy store. I understand now your suggestion that it might be difficult to find 10 "good" specimens in a day. Since we were new at this, we tended to keep everything that fell into our hands. We wrapped up everything because we didn't have time on site to pick and choose, and we didn't have time later to unwrap each package, so we ended up bringing it all back, and I am cleaning and sorting it now. We drove to Tudela to buy a small suitcase that we paid to bring home with us on the plane.
The pyrite crystals at Navajun occur embedded in a sedimentary rock formation. Fortunately, the host rock, called "matrix", is fairly soft and one can chisel around the pyrite crystals until they fall out of the host rock. Unfortunately, the pyrite crystals are brittle and can be damaged by shock from hammer blows. Often times the pyrite crystals are intergrown, and one can retrieve a cluster of crystals that can be as handsome as a single cube. Extracting a pyrite crystal or a grouping together with a bit of matrix material, that demonstrates how the crystal existed in its original setting, is a challenging task, but yields a more highly prized specimen.
Initially, the isolated cubes seemed most attractive and were easy and plentiful. As these became more common to us, we started to appreciate the clusters and groupings more, and finally the challenge of extracting a crystal in its surrounding matrix was appreciated as yet a finer choice. As I go through the samples that came home with me, I begin to see better which of these really are the better quality. So, yes, out of the 70 or 80 pieces I brought home, there are probably only 8 or 10 that really are pretty good. Many of the rest have significant defects.
You had mentioned both in your article and on the phone that Pedro is a good cook, and I have to admit that we were fairly astounded at the quality of the meals that he served to us. Here we were, out at the end of a narrow country road in a town of 16 being served a dinner worthy of a 5 star restaurant! It was great. Since we were there so late in the season, my wife and I were the only people in the casa. Even Pedro left us there for the night. We departed the next morning with our suitcase full of pyrite and the memories of a lifetime.
David Rusterholz with mine owner, Sr. Pedro Ansorena Conde
Here are the links to the two parts of my article on collecting pyrite in Navajun in our blog: Part 1 and Part 2. It was published as a single article in Rocks and Minerals, 90:1, 2015, 24-33, "Collecting Pyrite Crystals at Navajun, Spain".