Using decomposing galena, Mother Nature produces a wonderful suite of secondary lead minerals. Reaching deep into the earth — at times over 1,000 feet in desert regions — surface waters charged with oxygen and plant acids attack deep-seated sulfide ores, including galena, breaking down to release lead ions and combine with carbonates, sulfates, arsenates, or oxides. The process produces common colorful beauties like wulfenite, mimetite, pyromorphite vanadinite, and cerussite in abundance. Rare lead minerals like leadhillite also form.
CERUSSITE’S STRIKING CRYSTAL FORMATION
Cerussite can also appear as color-pale tan, pale green, bluish, yellow, or some other tint due to another mineral included as an impurity. Color plays only a minor role in the mineral’s value. Far more interesting and appealing is cerussite’s almost ingrained habit of forming any one of several twin forms, all very attractive and even beautiful. Unlike most crystals that twin, made up of two crystals, cerussite goes a step beyond ordinary twinning by combining several dozen crystals to twin in a very attractive unusual physical feature. Cerussite forms a greater assortment of twin forms than any other mineral, so these twins are most appealing and valuable whether the twin is stark white, has a tint of color, or water clear.
In addition to the varied and noteworthy twinning habits of cerussite, it’s interesting to learn the mineral crystallizes in the orthorhombic system. The term “ortho” indicates that the crystal has three internal axes around which it forms. Each axis is at an aright angle, just as in a cube, like a fluorite specimen. Orthorhombic crystals have rhombic faces, which means that every orthorhombic species crystal face is slanted, not square, and angled. Still, all slanted sides are at a right angle to each other. You see this best when a cerussite crystal is tabular. But cerussite does not form simple tabular rhombs very often. Instead, it tends to develop long slender crystals with slanted faces or as twinned crystals attached at the base, at an angle of about 60 degrees.
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Digging at the McDonald Ranch
In June of 2020, the Central Oregon Rock Collectors club went on a field trip to the McDonald Ranch near Ashwood, Oregon. The McDonald Ranch offers petrified wood, angelwing agate, and thundereggs.
MAGNETITE: A NATURAL HISTORY
An Iron Oxide that Changed the World
TETRAHEDRITE-TENNANTITE: Which is Which?
Unassuming, handsome, and confusing minerals
Amber and the Komboloi Tradition
Exploring the Science and Mindfulness Behind the Practice
CHANNELING A MOTHER ROCK
Mineral Constituents of the Chert Complex
Cerro de Trincheras
Trail, Museum & Petroglyphs South of the Border in Sonora, Mexico
Creating A Decorative Feature
STUDYING THE PAST OF Petrified Wood
Trust Plant Anatomy To Be Your Guide When Working In the Present
THE GARNET FAMILY
Spanning the Spectrum of Mineralogy
Ugly Rocks Can Contain Beautiful Treasures
From the outward appearance of certain ironstone or siderite nodules, they might seem to be ugly-looking dirty rocks, but they often hide beautiful treasures inside.