Greenstone is a common generic term for valuable, green-hued minerals and metamorphosed
igneous rockIgneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
s and stones, that were used in the fashioning of
hardstone carvingHardstone carving is a general term in art history and archaeology for the carving for artistic purposes of semi-precious stones, also known as gemstones, such as jade, rock crystal , agate, onyx, jasper, serpentine or carnelian, and for an object made in this way. Normally the objects are small,...
s such as jewelry, statuettes, ritual tools, and various other artefacts in early cultures. Greenstone artefacts may be made of
greenschistGreenschist is a general field petrologic term applied to metamorphic or altered mafic volcanic rock. The term greenstone is sometimes used to refer to greenschist but can refer to other rock types too. The green is due to abundant green chlorite, actinolite and epidote minerals that dominate the...
,
chlorastroliteChlorastrolite also known as Michigan Greenstone, is a green or bluish green stone. Chlorastrolite has finely radiated or stellate masses that have a "turtleback" pattern. The stellate masses tend to be chatoyant, meaning they have a changeable luster. This chatoyancy can be subtranslucent to...
, serpentine,
omphaciteOmphacite is a member of the pyroxene group of silicate minerals with formula: Si2O6. It is a variably deep to pale green or nearly colorless variety of pyroxene. Omphacite compositions are intermediate between calcium-rich augite and sodium-rich jadeite. It crystallizes in the monoclinic system...
,
chrysopraseChrysoprase, chrysophrase or chrysoprasus is a gemstone variety of chalcedony that contains small quantities of nickel. Its color is normally apple-green, but varies to deep green. The darker varieties of chrysoprase are also referred to as prase...
,
olivineThe mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....
,
nephriteNephrite is a variety of the calcium and magnesium-rich amphibole mineral actinolite . The chemical formula for nephrite is Ca25Si8O222. It is one of two different mineral species called jade. The other mineral species known as jade is jadeite, which is a variety of pyroxene...
, chloromelanite among other green-hued minerals. The term also includes
jadeJade is an ornamental stone.The term jade is applied to two different metamorphic rocks that are made up of different silicate minerals:...
and
jadeiteJadeite is a pyroxene mineral with composition NaAlSi2O6. It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0 depending on the composition. The mineral is dense, with a specific gravity of about 3.4. Jadeite forms solid solutions with other pyroxene endmembers such as augite and diopside ,...
, although these are perhaps more frequently identified by these latter terms.
Greenstone minerals were presumably selected for their color rather than their chemical composition. In
archaeologyArchaeology, or archeology , is the study of human society, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts and cultural landscapes...
therefore, having a loosely applied general term is at least partially influenced by the observation that ancient cultures often used and considered these various green-hued materials as interchangeable.
The greenish hue of these rocks generally derives from the presence of minerals such as
chloriteThe chlorite ion is ClO2−. A chlorite is a compound that contains this group,with chlorine in oxidation state +3. Chlorites are also known as salts of chlorous acid.-Oxidation states:...
,
hornblendeHornblende is a complex inosilicate series of minerals .It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole....
, or
epidoteEpidote is a calcium aluminium iron sorosilicate mineral, Ca2Al2O, crystallizing in the monoclinic system. Well-developed crystals are of frequent occurrence: they are commonly prismatic in habit, the direction of elongation being perpendicular to the single plane of symmetry. The faces are often...
.
Ancient China and
MesoamericaMesoamerica is a region and culture area in the Americas, extending approximately from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica, within which a number of pre-Columbian societies flourished before the Spanish colonization of the Americas in the 15th and...
are particularly noted for the prevalence and significance of greenstone (particularly jade) usage. Greenstones also figure prominently in the indigenous cultures of southeastern
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, and among the Māori of
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
(known as Pounamu).
External links