Thursday, April 25, 2019
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Racracancha Cerro

Rock & Gem Kids: Manganoan Calcite

By Jim Brace-Thompson Calcite comes in a remarkable variety of shapes and colors. One beautiful variety that is highly sought by collectors is manganoan calcite....
Rock formations near San Andreas Fault

Rock & Gem Kids: Earthquake Faults

By Jim Brace-Thompson Portions of our continents are stable, and the earth seldom moves under our feet. But in places like my home state of...

Rock & Gem Kids: Examining Ozokerite

By Jim Brace-Thompson “What is this stuff?” I asked myself as I picked up a lightweight chunk from a silent auction table at a gem...

Rock & Gem Kids: Setting Sights on Spinel

By Jim Brace-Thompson Spinel (magnesium aluminum oxide) forms beautiful crystals that are sometimes confused for the brilliant-red gem variety of corundum known as ruby. Unlike...

Rock & Gem Kids: Fossil sand dollars

By Jim Brace-Thompson Beachcombers and fossil hunters alike love sand dollars! They belong to the phylum Echinodermata, which includes marine animals like starfish, sea cucumbers,...