Deposits of iron ore accumulated in the several ways referred to above may be metamorphosed and changed to hematite and magnetite.
The minerals at contact are quartz, biotite, magnetite and hornblende.
magnetite is loadstone ore; the powder is reddish black, and the ore, dark brown to black.
There is some sericite present, also magnetite, resulting from the decomposition of the biotite.
Here the magnetite forms a great tabular vertical body lying between porphyry and syenite.
It is also somewhat stained by the decomposition of the magnetite.
Haematite is sometimes magnetic, and A. Liversidge has shown that magnetite is probably present.
The usual association with apatite and magnetite crystals is noted.
magnetite is often accompanied by rocks containing garnet, epidote and hornblende.
magnetite, an oxide of iron, has developed a candle-power with but one half of one watt.