Opalized “conk” wood from Royal Peacock Opal Mine, Virgin Valley, Nevada.
4 inches long x 2.5 inches wide
This piece was mined prior to 1962 and won best in show at the Tucson Gem and Mineral show in 1990. This is ‘conk,’ which is an opal replacement of cavities in wood thought to be formed by a fungal disease.
Virgin Valley opals are found in layers of clay that were formed when volcanic ash filled an ancient lake millions of years ago. The surrounding forests were also choked with the ash. The lake had twigs and limbs and rotting wood collected in its coves. The buried wood decayed and left lifelike cavities as mementos of their presence.
Heat and pressure formed a silica gel that percolated through the ash and filled the cavities. It gradually hardened into opal. Virgin Valley opals are predominately limb casts embedded in clay beds. Most limbs come from an ancient tree species called Cryptomeria, a relative of the Sequoia. A few opalized limbs have also been identified as coming from Fir, Pine, Oak, Chestnut, Maple, and Elm, as well as Ginkgo.
4 inches long x 2.5 inches wide
This piece was mined prior to 1962 and won best in show at the Tucson Gem and Mineral show in 1990. This is ‘conk,’ which is an opal replacement of cavities in wood thought to be formed by a fungal disease.
Virgin Valley opals are found in layers of clay that were formed when volcanic ash filled an ancient lake millions of years ago. The surrounding forests were also choked with the ash. The lake had twigs and limbs and rotting wood collected in its coves. The buried wood decayed and left lifelike cavities as mementos of their presence.
Heat and pressure formed a silica gel that percolated through the ash and filled the cavities. It gradually hardened into opal. Virgin Valley opals are predominately limb casts embedded in clay beds. Most limbs come from an ancient tree species called Cryptomeria, a relative of the Sequoia. A few opalized limbs have also been identified as coming from Fir, Pine, Oak, Chestnut, Maple, and Elm, as well as Ginkgo.