minute fragments, with rose-coloured cement, sometimes intense, and again diffused, bearing a great resemblance to red porphyry, consequently of lovely effect in workmanship. The most beautiful specimens of the calcarea ruiniforme are to be found in the neighbourhood of Gesualdo and Frigento, in the province of Avellino, and the second variety is more common in the district of Melfi than anywhere else. If the limestone of this series contains almost invariably some clay, the clays, on the other hand, are always mixed with some proportion of carbonate of lime, which gives them a marly character. They are sometimes compact (amorphous), but more frequently divided into thin laminæ, without losing the property of forming with water a ductile paste. They are usually of a gray sky colour, and in Lucania are not unfrequently red. These rocks on one side pass by imperceptible degrees into limestone; on the other beginning to contain minute particles of mica and small grains of sand, the latter gradually becoming more abundant, they change into sandstone. The sandstone itself, owing to the size of the grains of quartz, and their abundance or scarcity, and also to their varying degree of tenacity, present innumerable differences, which are of no importance. They possess, for the most part, the characteristics of true Macigno; in some cases are good for sharpening edged tools, and in others may be used with advantage for making bricks or crucibles capable of bearing a high temperature. The Limonite is seldom found pure, and its deposits are so scarce, that they can with difficulty be profitably used for the extraction of iron; nevertheless, mixed with carbonate of lime, it is rather frequently found in each of the three preceding kinds of rocks, especially in the limestones and marls.
Ferruginous sandstones, occasionally mixed with deposits of Limonite, are not scarce in the district of the Vulture, and it is requisite to take care not to confuse them with volcanic productions. When the limonite unites with marl, it occasions such strange forms, that the naturalist no less than the uninitiated must regard them with astonishment. Besides what I have said relative to these Eagle stones, of which beautiful specimens are to be found in the district of Gerace, there are some remarkable varieties in the Fucino district near Pietraroia, which, from their
