Apache Tears are a type of Black Obsidian, but they have a more friendly vibration than some of the other types of Obsidian.
Maybe it is their strange out-of-shape appearance, that makes you comfortable with them.
They are strong stones for grounding and protection, and to aid you to clear negative emotions that may be holding you back.
They are volcanic stones, that may be partly transparent. Their color is very dark brown to black in color.