6. The three views of a geometric body are shown in Figure 1. Its side view is an equilateral triangle with a side length of 1, and its top view is a rhombus formed by two equilateral triangles. Then the volume of this geometric body is $($.
(A) 1
(B) $\frac{1}{2}$
(C) $\frac{1}{4}$
(D) $\frac{1}{8}$