Hornblend

Hornblend is common in some of our rocks in various amorphous forms. In this specimen, where it occurs in its close, very compact state, it is of a greenish black colour; but as it seems to spread and become less compact, the green hue grows more and more sensible. It is said by many authors in this latter state to form Greenstone with Quartz and Feldspar, or Grunstein of the Germans; but other substances may form Greenstones: hence the necessity of noticing it. Chlorite may be often confounded with it when the Hornblend is divided; but Chlorite is never so dark, hard , or compact as Hornblend, which can with difficulty be scraped with a knife, and composes the darker parts in this specimen. It takes a good polish as well as the white pans, which are hard Feldspar. The green mixture is rather granular and softer, containing Feldspar. This Stone has several conspicuous particles of Sulphuret of Iron, and of Magnetic Iron. It was part of a Boulder from a gravel-pit near York, and may be called an Hornblend Porphyry with Pyrites and Iron.