Early into chapter two of John Steinbeck's The Pearl, the morning is described as being "young" and possessing a "hazy mirage." In order to understand what this image looks like, one can dissect it. A haze is the same thing as a mist or fog. This tends to happen when the temperature of the ground (or water, as with a lake or ocean) is drastically different from the temperature of the air above it). This makes the scene look blurry. A mirage is an optical illusion created by light refracting off of something. For example, when looking at a stretch of pavement, it sometimes looks like water is covering the ground. This is considered a mirage.
Therefore, a "hazy mirage" is where the mist over the water (as defined in the story) showed things which were not there. The text states that although the "people of the Gulf believed in spirits and imaginations, they did not trust things they saw when the images were distorted by the mists rising off the water.