The coal industry of Maverick County is located along a section of the Olmos Coal Formation immediately north of Eagle Pass. Mining operations developed by Dolch at Dolchburg and by the Olmos Coal, Coke, and Oil Company at Olmos were the largest coal producers in Texas around the turn of the 20th century.
Those photos still fade over time, plastic doesn't prevent the materials from fading or deteriorating. Pencil that's the old lead pencils, or the new graphite pencils will not fade. Graphite is the most stable form of carbon. It's color is grey rather than black, so the line will be lighter than a black color pencil, but they are not susceptible to fading, they are extremely stable.
Pencil Does Not Fade. In the past I have blogged about my joy of journaling in a Moleskine, and last week I shared how I'm using the ESV Journaling Bible. In both books I make the vast majority of my notes in pencil, not pen. People are often surprised that I favor a pencil, and ask if I'm afraid the writing will fade. The short answer is, No. Pencil doesn't fade. When I say pencil, I'm referring to a mechanical pencil (typically this one).