This is a Xlarge Icons icon. We've made it in iOS style, first introduced in iOS version 7 and supported in all later releases up until now (at least iOS 11). This style is based on thin two-pixel lines and is optimized for 50x50 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 12,400 icons, all in the same style and quality.
This looks like an image icon on Microsoft Windows. There are 2 rectangles, one inside the other slightly smaller to create a picture frame look. Inside is a jagged line to represent a mountain range and a small circle above this line looks like the sun or moon.