Although cryolite is known as "ice-stone" (_Eisstein_), it is not to be confused with "ice-spar" (_Eisspath_), which is a vitreous kind of felspar termed "glassy felspar" or rhyacolite. (F. W. R.*)
CRYPT (Lat. _crypta_, from the Gr. [Greek: kryptein], to hide), a vault or subterranean chamber, especially under churches. In classical phraseology "crypta" was employed for any vaulted building, either partially or entirely below the level of the ground. It is used for a sewer (_crypta Suburae_, Juvenal, _Sat._ v. 106); for the "carceres," or vaulted stalls for the horses and chariots in a circus (Sidon. Apoll. _Carm._ xxiii. 319); for the close porticoes or arcades, more fully known as "cryptoporticus," attached by the Romans to their suburban villas for the sake of coolness, and to the theatres as places of exercise or rehearsal for the performers (Plin. _Epist._ ii. 15, v. 6, vii. 21; Sueton. _Calig._ 58; Sidon. Apoll, lib. ii. epist. 2); and for underground receptacles for agricultural produce (Vitruv. vi. 8, Varro, _De re rust._ i. 57). Tunnels, or galleries excavated in the living rock, were also called _cryptae_. Thus the tunnel to the north of Naples, through which the road passes to Puteoli, familiar to tourists as the "Grotto of Posilipo," was originally designated _crypta Neapolitana_ (Seneca, Epist. 57). In early Christian times _crypta_ was appropriately employed for the galleries of a catacomb, or for the catacomb itself. Jerome calls them by this name when describing his visits to them as a schoolboy, and the term is used by Prudentius (see CATACOMBS).
A crypt, as a portion of a church, had its origin in the subterranean chapels known as "confessiones," erected around the tomb of a martyr, or the place of his martyrdom. This is the origin of the spacious crypts, some of which may be called subterranean churches, of the Roman churches of S. Prisca, S. Prassede, S. Martino ai Monti, S. Lorenzo fuori le Mura, and above all of St Peter's--the crypt being thus the germ of the church or basilica subsequently erected above the hallowed spot. When the martyr's tomb was sunk in the surface of the ground, and not placed in a catacomb chapel, the original memorial-shrine would be only partially below the surface, and consequently the part of the church erected over it, which was always that containing the altar, would be elevated some height above the ground, and be approached by flights of steps. This fashion of raising the chancel or altar end of a church on a crypt was widely imitated long after the reason for adopting it ceased, and even where it never existed. The crypt under the altar at the basilica of St Maria Maggiore in Rome is merely imitative, and the same may be said of many of the crypts of the early churches in England. The original Saxon cathedral of Canterbury had a crypt beneath the eastern apse, containing the so-called body of St Dunstan, and other relics, "fabricated," according to Eadmer, "in the likeness of the confessionary of St Peter at Rome" (see BASILICA). St Wilfrid constructed crypts still existing beneath the churches erected by him in the latter part of the 7th century at Hexham and Ripon. These are peculiarly interesting from their similarity in form and arrangement to the catacomb chapels with which Wilfrid must have become familiar during his residence in Rome. The cathedral, begun by Æthelwold and finished by Alphege at Winchester, at the end of the 10th century, had spacious crypts "supporting the holy altar and the venerable relics of the saints" (Wulstan, _Life of St Æthelwold_), and they appear to have been common in the earlier churches in England. The arrangement was adopted by the Norman builders of the 11th and 12th centuries, and though far from universal is found in many of the cathedrals of that date. The object of the construction of these crypts was twofold,--to give the altar sufficient elevation to enable those below to witness the sacred mysteries, and to provide a place of burial for those holy men whose relics were the church's most precious possession. But the crypt was "a foreign fashion," derived, as has been said, from Rome, "which failed to take root in England, and indeed elsewhere barely outlasted the Romanesque period" (_Essays on Cathedrals_, ed. Howson, p. 331).