This is a Time Span 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 12,800 icons, all in the same style and quality.
The outer shape is a circle. In the center of the circle is a dot with two straight lines extending towards the outer circle. One line is shorter and points in towards the right and the other line is longer and points towards the upper left. A one eighth section of the circle is filled in with parallel lines.