An analcime coated vug with a calcite crystal inside. There are balls of nontronite scattered throughout the vug. When the vugs are opened, the nontronite becomes black. But before to air or light, however, the nontronite is blue - as can be seen when it is included in the calcite.
This picture is taken with a Canon MP-E 65.
The calcite crystal is slightly less than 1 mm across vertex to vertex.