Bulletin of the United States Geological Survey--The Nature and Origin of Deposits of Phosphate and Lime . Fig. 22. Section at Cubach, Nassau, Prussia. After D. C. Davies : Geological Magazine, London, , clay; B, phosphate of lime; C, manganese; D, dolomite. The phosphorite is found in a great variety of forms. It is generallymassive, fibrous, earthy, porous, jasper-like, kidney-shaped, stalactitic,or nodular. Occasionally there are found in it minute crystals ofapatite (Davies). Sometimes, also, it occurs as an incrustation, and itis then known as staffelite, from its abundance near the
Bulletin of the United States Geological Survey--The Nature and Origin of Deposits of Phosphate and Lime . Fig. 22. Section at Cubach, Nassau, Prussia. After D. C. Davies : Geological Magazine, London, , clay; B, phosphate of lime; C, manganese; D, dolomite. The phosphorite is found in a great variety of forms. It is generallymassive, fibrous, earthy, porous, jasper-like, kidney-shaped, stalactitic,or nodular. Occasionally there are found in it minute crystals ofapatite (Davies). Sometimes, also, it occurs as an incrustation, and itis then known as staffelite, from its abundance near the town of Fig. 23. Section at Staffel, Nassau, Prussia. After D. C. Davies : Geological Magazine, London, , dolomite; B, clay; C, phosphate of lime. This mineral is, generally, white, yellow, green, or brown in color, andoccasionally translucent. The other varieties are of almost all colors,white, yellow, red, gray, blue, green, brown, or black. Occasionally abrecciated variety is found, but the larger part of the deposit is of themassive The hardness varies from 1 to 5. With the phosphor-ite occasionally occur deposits of crystalline hematite and manganeseore. These minerals are most common on the outside edges of thephosphate-bearing area, but are also found with it in the same amount of phosphate of lime in the phosphorite is very variable,averaging from 60 to 92 per cent, (see analyses). It is generally richestwhen associated with the least hematite and manganese and, when freefrom the former mineral, it makes an excellent superphosphate. Amongthe other minerals ass
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