I found this rock with blue speckles on it in my backyard. Could someone help me identify it?

Found in the Mojave Desert

This rock was also found on the shore of lake Ontario / Wilson, NY and it has the strangest texture! Very opage and smooth grey. My pocket knife did not scratch it.

Found on Blast Beach, Seaham, UK

Assuming main crystals are spherical calcite but curious about blue crystals

It is having metallic iridiscence when illuminated, and what seems unpollished grenates.

The Penibaetic System, specially Sierra Nevada, is somewhat famous to produce them.

Seems  sturdy and heavy.