That is likely granite. At another house it is all calcite ... all embedded in a matrix of volcanic glass and feldspar crystals. Credit: Erik Klemetti Suddenly, there is a lot more color and the rock ...

Instead, Yosemite granite had a deeper source. Huge volumes of magma -- hot, molten rock -- pooled up in large chambers below that ancient volcanic landscape. Just as ice crystals develop on ...

Large crystals found in geodes and other rocks are relatively rare ... iron, marble, and granite. Silicates—including quartz, mica, olivine, and precious minerals such as emeralds—are the ...

Crystals? Stones? Gems? Rocks? What’s the difference ... Stones can vary in size and application, from massive blocks of granite used in architecture to smooth pebbles collected from riverbanks.