Magnetic Minerals In Granite

Bouchez and k.

Magnetic minerals in granite.

Hysteresis is the variation of magnetization with applied field and illustrates the ability of a material to retain its magnetization even after an applied field is removed. The rock granite cannot be magnetic but it can contain one or more minerals that are magnetic and if present those minerals would make that particular sample slightly magnetic in the areas surrounding those particular minerals. Magnetite also called lodestone or magnetic iron ore iron oxide mineral fefe 2 o 4 or fe 3 o 4 that is the chief member of one of the series of the spinel q v group minerals in this series form black to brownish metallic moderately hard octahedrons and masses in igneous and metamorphic rocks and in granite pegmatites stony meteorites and high temperature sulfide veins. Magnetite is a rock mineral and one of the main iron ores with the chemical formula fe 3 o 4 it is one of the oxides of iron and is ferrimagnetic.

Rock magnetism is the study of the magnetic properties of rocks sediments and soils the field arose out of the need in paleomagnetism to understand how rocks record the earth s magnetic field. Figure 9 illustrates this phenomenon in the form of a plot of. The magnetic minerals are few but the property is important because of this fact. Magnetism occurs most often when there is an imbalance in the structural arrangement of the iron ions.

If you have a grani. The concept of hysteresis is fundamental when describing and comparing the magnetic properties of rocks. The mineral content of granite includes quartz feldspar and hornblende which combine in flecks to create this solid stone. Hattori a aottawa carleton geoscience center department of geology university of ottawa 161 louis pasteur ottawa ont kin 6n5 canada.

It is the most magnetic of all the naturally occurring minerals on earth. The mineral magnetite is named after this characteristic. In that regard yes absolute black and most rocks in the granite family contain iron rich minerals that will weakly attract a magnet. It is attracted to a magnet and can be magnetized to become a permanent magnet itself.

Magnetic susceptibilities of selected rocks and minerals rock mineral chemical formula density volume k mass z 10 3 kg m 3 10 4 si 10 4 m3kg references igneous rocks andesite basalt diabase diorite gabbro granite peridotite porphyry pyroxenite rhyolite igneous rocks average acidic igneous rocks. In general darker rocks have more of these minerals than lighter rocks again this only applies to the granite family of rocks i e. Rock rock hysteresis and magnetic susceptibility. 190 magnetic properties table 1.

This remanence is carried by minerals particularly certain strongly magnetic minerals like magnetite the main source of magnetism in lodestone an understanding of remanence helps paleomagnetists to. Once a specimen is established as magnetic identification becomes a rather routine exercise.