70 
GLOSSARY. 
Gramine2E, the order of plants to which grasses belong. Etym., 
gramen, grass. 
Granite. An unstratified or igneous rock, generally found inferior 
to or associated with the oldest of the stratified rocks, and some- 
times penetrating them in the form of dikes and veins. It is 
composed of three simple minerals, felspar, quartz, and mica, 
and derives its name from having a coarse granular structure ; 
granum, Latin for grain. Westminster, Waterloo, and London 
bridges, and the paving-stones in the carriage-way of the Lon- 
don streets are good examples of the most common varieties of 
granite. 
Grauwacke, a German name, generally adopted by geologists for 
the lowest members of the secondary strata, consisting of sand- 
stone and slate, and which form the chief part of what are 
termed by some geologists the transition rocks. The rock is 
very often of a grey colour, hence the name, grau being German 
for grey, and wacke being a provincial miner's term. 
Greensand. Beds of sand, sandstone, limestone, belonging to the 
Cretaceous Period. See Table II. F, p. 390. The name is 
given to these beds, because they often, but not always, contain 
an abundance of green earth or chlorite scattered through the 
substance of the sandstone, limestone, &c. See vol. iii. p. 324. 
Greenstone, a variety of trap, composed of hornblende and felspar. 
Grit, a provincial name for a coarse-grained sandstone. 
Gypsum, a mineral composed of lime and sulphuric acid, hence 
called also sulphate of lime. Plaster and stucco are obtained 
by exposing gypsum to a strong heat. It is found so abun- 
dantly near Paris, that Paris plaster is a common term in this 
country for the white powder of which casts are made. The 
term is used by Pliny for a stone used- for the same purposes by 
the ancients. The derivation of it is unknown. 
Gvpseous, of, or belonging to, gypsum. 
Gyrogonites. Bodies found in fresh-water deposits, originally sup- 
posed to be microscopic shells, but subsequently discovered to 
be the seed-vessel of fresh-water plants of the genus chara. See 
vol. ii. p. 273, and 2d Edit. p. 280. Etym. yvpog, gyros, curved, 
and yovoQj gonos, seed, on account of their external structure. 
Hemiptera, an order of insects, so called from a peculiarity in their 
wings, the superior being coriaceous at the base, and mem- 
branous at the apex, ypiav, hemisu, half, and tcte^ov, pteron, 
wing. 
Hornblende, a simple mineral of a dark green or black colour, 
