What is the rock Schist made from?? (Other words, what rock was it before it changed into Schist?)?

Question

-Confused-

Answer 1

phyllite, basalt, slate, shale. There are many types of schist. It is defined mainly as being a plated metamorphic rock in which the mineral crystals can bee seen with the naked eye.

Answer 2

Sedimentary Siltstone is Metamorphosed into Slate then into Schist.
With further Metamorphism Schist becomes Gneiss.
Schist is foliated perpendicular to the direction of metamorphic pressure and show distinctive layering or plating for wont of a better word called 'schistostity' (not sure of the spelling).
Schist is made up of flat platy minerals that align themselves perpendicular to the direction of pressure.

Answer 3

Gaspode did a really thorough job with that answer but here's a bit more.

What is schist in general?

Schist is a widespread metamorphic rock. It has been subjected to extremes of pressure, temperature, or both, within the earth. These extremes can do several things to rocks. In the case of schist, they cause the minerals within the parent rock to realign (we call that 'recrystallization') into very thin layers (called 'planes') perpendicular (one right next to the other , like phyllo dough) to the direction of compression.

In addition, schists are usually micaceous (they have a lot of shiny mica in them) and often also contain needle-like amphibole crystals (long thin needes of usually dark-colored crystals).


Where does schist come from?

Most schists have probaby come from clays and muds which have passed through a series of metamorphic processes involving the production of shales and slates as intermediate steps. Certain schists have been derived from fine-grained igneous rocks such as basalts and tuffs. Most schists are mica schists, but graphite and chlorite schists are also common.

Schists are named for their prominent or perhaps unusual mineral constituents, such as garnet schist, tourmaline schist, glaucophane schist, etc.

Put another way:
Schist is a metamorphic rock that comes in almost infinite variety, but its main characteristic is hinted at in its name: schist comes from the ancient Greek for "split".

Schist is a rock formed by dynamic high-temperature, high-pressure metamorphism that involves a lot of strain. The high pressure and strain flattens and elongates the grains of mica, hornblende, and other minerals present in the parent rocks into many very thin layers. At least 50 percent of the mineral grains in schist are aligned this way (less than 50 percent makes it gneiss).

The first three links below are picture galleries devoted to schists.