There are several ways that non-foliated rocks can be produced.
Metamorphic rocks are broken down into two groups based on whether the rock is foliated or non-foliated.
Slate, schist and gneiss are all foliated metamorphic rocks.
British Dictionary definitions for foliated
foliated
/ˈfəʊlɪˌeɪtɪd/
adjective
1.
(architect) ornamented with or made up of foliage or foils
2.
(of rocks and minerals, esp schists) composed of thin easily separable layers
3.
(esp of parts of animals or plants) resembling a leaf
foliate
adjective (ˈfəʊlɪɪt; -ˌeɪt)
1.
relating to, possessing, or resembling leaves
in combination: trifoliate
2.
(of certain metamorphic rocks, esp schists) having the constituent minerals arranged in thin leaflike layers
verb (ˈfəʊlɪˌeɪt)
3.
(transitive) to ornament with foliage or with leaf forms such as foils
4.
to hammer or cut (metal) into thin plates or foil
5.
(transitive) to coat or back (glass, etc) with metal foil
6.
(transitive) to number the leaves of (a book, manuscript, etc) Compare paginate
7.
(intransitive) (of plants) to grow leaves
Word Origin
C17: from Latin foliātus leaved, leafy
Word Origin and History for foliated
foliate
adj.
1620s, from Latin foliatus "leaved, leafy," from folium (see folio).
v.
1660s, "to apply silver leaf," from Latin foliatus "leaved, leafy," from folium (see folio). Meaning "to put forth leaves" is from 1775. Related: Foliated; foliating.
foliated in Science
foliation
(fō'lē-ā'shən) The set of layers visible in many metamorphic rocks as a result of the flattening and stretching of mineral grains during metamorphism.