White Raven Mine, Ward Mining District, Boulder County, Colorado, USAi

Regional Level Types
White Raven Mine	Mine
Ward Mining District	Mining District
Boulder County	County
Colorado	State
USA	Country

“Has been a heavy producer of silver in past years, especially in 1913, and the immediately following years. It is estimated that $800,000 in lead and silver have been produced since 1913. The ore bodies of this mine are especially interesting because they are of an unusual type in the Ward District, which was known in the early days for its gold production.”

“The White Raven Mine is located on a fissure vein in massive gray pre-Cambrian granite, which contains a few inclusions of schist. Intruded into the granite, roughly parallel to, and in places cut by the vein, is a dike of monzonite porphyry which is probably genetically related to the vein. The White Raven vein strikes approximately west and dips steeply to the north.”

“The lead-silver ore was formed in a fissure which resulted from the reopening and brecciation of an older vein of gold-bearing Quartz-pyrite-chalcopyrite ore. Brecciated fragments of this ore are found in many places in the vein and are covered in most cases by a coating of galena and siderite. These relations prove that the Iead-silver vein is of a later date than the quartz-pyrite-chalcopyrite mineralization.”

“The following minerals have been found in important amounts in the ore shoots of the lead-silver vein: horn quartz, manganiferous siderite, barite, galena, and native silver. Other minerals occurring in minor amounts are pyrite, sphalerite, and calcite. The lower levels of the mine, at present inaccessible, have been reported to contain tennantite in addition to the minerals mentioned. In many places in the mine the minerals occur as layered coatings in openings or "vugs,” many of which are a foot or more across. These openings have permitted the free growth of crystals of siderite, galena, and barite.” (Wahlstrom, Ernest E., (1935))

He describes the siderite as:
“A lining in "vugs,” where it forms well developed crystals with the other vein minerals. The crystals vary considerably in size. The smallest crystals are microscopic, and the largest crystals are as much as three quarters of an inch wide. The crystals appear as flat rhombohedrons, and upon close inspection are seen to have curved surfaces similar to those frequently found on dolomite crystals.”

The baryte he describes as:
“Occurs as simple, tabular crystals partly or completely embedded in the siderite, indicating that it started to form in the veins before the precipitation of the first generation of siderite was complete. Ilowever, in many specimens that were examined, the second generation of siderite has completely covered the barite, so that its presence may be observed only by examining a cross-section of the vein. The largest crystals of barite are about three quarters of an inch long and half an inch wide. The crystals are zoned and have a transparent core surrounded by a thin layer of white barite. Many of the barite crystals are encrusted with small crystals of galena and siderite"

He then goes on to describe the galena:
“The galena is found in crystals showing a combination of cube and octahedron. Many of the galena crystals are distorted and have tabular or elongated shapes because of rapid growth in a direction parallel to an octahedron face. This type of crystal is shown in figure 7. The surfaces of the galena crystals have a dull appearance, and a few crystals show well developed etch patterns formed, possibly, by the action of solutions of the same origin as those from which the galena and other vein minerals were deposited. The largest galena crystals are about three quarters of an inch in diameter.”

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