LEPIDOLITE

lepidolite, or lithia-mica, a mineral of the mica group (see mica). it is a basic aluminium, potassium and lithium fluo-silicate, with the approximate formula kli [al(oh, f)2] al(sio3)3. lithia and fluorine are each present to the extent of about 5%; rubidium and caesium are sometimes present in small amounts. distinctly developed monoclinic crystals or cleavage sheets of large size are of rare occurrence, the mineral being usually found as scaly aggregates, and on this account was named lepidolite (from gr. [greek: lepis], scale) by m. h. klaproth in 1792. it is usually of a lilac or peach-blossom colour, but is sometimes greyish-white, and has a pearly lustre on the cleavage surfaces. the hardness is 21⁄2-4 and the sp. gr. 2.8-2.9, the optic axial angle measures 50°-70°. it is found in pegmatite-veins, often in association with pink tourmaline (rubellite) and sometimes intergrown in parallel position with muscovite. scaly masses of considerable extent are found at rozena near bystrzitz in moravia and at pala in san diego county, california. the material from rozena has been known since 1791, and has sometimes been cut and polished for ornamental purposes: it has a pretty colour and spangled appearance and takes a good polish, but is rather soft. at pala it has been extensively mined for the preparation of lithium and rubidium salts. other localities for the mineral are the island of uto in sweden, and auburn and paris in maine, u.s.a.; at alabashka near mursinka in the urals large isolated crystals have been found, and from central australia transparent cleavage sheets of a fine lilac colour are known. the lithium-iron mica _zinnwaldite_ or _lithionite_ is closely allied to lepidolite, differing from it in containing some ferrous iron in addition to the constituents mentioned above. it occurs as greyish silvery scales with hexagonal outlines in the tin-bearing granites of zinnwald in the erzgebirge, bohemia and of cornwall. (l. j. s.) lepidoptera (gr. [greek: lepis], a scale or husk, and [greek: pteron], a wing), a term used in zoological classification for one of the largest and best-known orders of the class hexapoda (q.v.), in order that comprises the insects popularly called butterflies and moths. the term was first used by linnaeus (1735) in the sense still accepted by modern zoologists, and there are few groups of animals as to whose limits and distinguishing characters less controversy has arisen. [illustration: after edwards, riley and howard's _insect life_, vol. 3 (u.s. dept. agr.). fig. 1.--e, _crytophasa unipuctata_, donov., australia. a, larva; c, pupa, natural size; b, 2nd and 3rd abdominal segments of larva; d, cremaster of pupa, magnified.] _characters._--the name of the order indicates the fact that the wings (and other parts of the body) are clothed with flattened cuticular structures--the scales (fig. 7)--that may be regarded as modified arthropodan "hairs." such scales are not peculiar to the lepidoptera--they are found also on many of the aptera, on the psocidae, a family of corrodentia, on some coleoptera (beetles) and on the gnats (culicidae), a family of diptera. the most distinctive structural features of the lepidoptera are to be found in the jaws. the mandibles are mere vestiges or entirely absent; the second maxillae are usually reduced to a narrow transverse mentum which bears the scale-covered labial palps, between which project the elongate first maxillae, grooved on their inner faces, so as to form when apposed a tubular proboscis adapted for sucking liquid food. all lepidoptera are hatched as the eruciform soft-bodied type of larva (fig. 1, a) known as the caterpillar, with biting mandibles, three pairs of thoracic legs and with a variable number (usually five pairs) of abdominal prolegs, which carry complete or incomplete circles of hooklets. the pupa in a single family only is free (i.e. with the appendages free from the body), and mandibulate. in the vast majority of the order it is more or less obtect (i.e. with the appendages fixed to the cuticle of the body) and without mandibles (fig. 1, c). [illustration: from riley and howard, _insect life_, vol. 7 (u.s. dept. agr.). fig. 2.--a, feeler of saturniid moth (_telea polyphemus_). b, c, tips of branches, highly magnified.] [illustration: after a. walter (_jen. zeits. f. naturw._ vol. 18).