This is color-enhanced Mexican Crazy Lace Agate which is normally white opaque with swirling patterns. To emphasize these beautiful patterns, the blue color is added. Color enhancing is common amongst agates to make them fashionably relevant. Although colors are enhanced the healing properties remain the same.
Lace agates are said to keep the wearer well-balanced while helping to banish fear.
Mohs hardness 6.5-7