A white rattlesnake spotted Wednesday at a Texas park has produced a collective shudder across the country, after a photo of the snake was shared thousands of times on Facebook. It’s not an albino. Called a banded rock rattlesnake, the seldom seen species of pit viper has a spotty distribution in only three states along the Mexican border (Arizona, New Mexico, and Texas), and is known for having a powerful bite, say experts. The photo was posted Wednesday by The Wyler Aerial Tramway State Park in Texas, a 195-acre park within the Franklin Mountains. “We had this little friend come...