pofito, quadratulo centrali minore non parallelo, imo contrario, difcolore,
ant & macula margacea1 fufea quadratica contraria notato. Aggregatæ hæ
cryftalli, una cum intermixtis tenerrimis, diaphanisque & tetragonis pliimbi
fpatofi lamellis infidebant cruftæ calcareo - fpatofæ, drufico - cryftallinæ,
coalitæ e cryftällulis hyodonticis; calcareum æquabilem albido- grifefcen-
tem, tends nigro - magnefiacis piflum, & marga martiali rufa oblitum , in-
cruftante.
LXXX.
Plumbum fpatofum partim faturo - partim emoriente jam ceræ flavæ
colore , femidiaphanum , nitens cryftallinum ; cryftallis ex parte tefiaro-
decaëdris, ex parte felenitico- decaëdris, ociodecaëdrisque compreffiffimis;
turn & tetragono-pyramidatis acicularibus, copiofiffime accumulatis; fcala-
riter, aut et temere, confufe, nullaque lege , & ordine mutuo fibi invicem
fuperimpofitis, vereque connatis, nec heterogeneo inter fe vifco conglutina-
tis. Sic rariffimam fpatofi plumbi varietatem, aliqua faltem ratione me de-
nique adumbrare poffe exiftimo. Matrici equidem jam nullf, fed inhærebat
certe quondam plumbo fpatofo flavo lolido , margam induratam lapideam
(cuniculi fanélæ Catharinæ in pariete) obducenti ; eftque mafia e metis cryftallis
plumbaceo fpatofis inordinate accumulatis, nec alieno glutine unitis
concreta. E x altera fcilicet parte cryftallis majufculis piano - compreffis,
v ix lineam craffis, felenitico - decaëdris, turn & oftodecaëdris conferte ag-
gregatis, fefeque mutuo decuflantibus. E x altera contra : cryftallis magis,
minusve ordinate tefiaro - decaëdris, id eft cubico - feleniticis, refefta ca~
rinæ circumferentialis acie; quibus dein, ubi fruftulum cavernofum eft, cryftalli
pâriter plumbaceo - fpatofæ infidept admodum graciles, quæ fubulatæ,
imoimo
aciculares credi poffent, re autem vera, ut microfcopium docet, tetragono
pyramidatæ lunt ; e bafi quadrata perquam exigea, & quatuor trian-
gulis' ifofçelicis altis, in unum acumen aciciilare convergentibus compofitæ,
dilute flavæ, diaphanæ, nitpntes. Ortas primo intuitu ex ftillicidio credas;
a t microlcopium veras cryftallos efle demonftrat ; quod & fitus earumdern
exhibet præterea, utpote quarum aliquæ perpendiculariter erectæ, aliæ per-
pendiculariter pendulæ, aliæ denique horizontales, a dextra verfus finiftram,
& viciflim, tendentes funt. Quas in fcalares illinc turriculas exaltatas cer-
lûs, lamellæ verius, quam veræ cryftalli funt; graciles illæ admodum, tetragono
- fubrotundæ, mutuo quidern, non tarnen eentraliter, oppofitis imo,
extimisque duntaxat perimetri fegmentis , fibi incumbentes, & alternatim
utrinque inftar. graduum fcalæ cujusdam, exftantes. E x Catharein in der
Wand.
LXXXL
Plumbum fpatofum nigrum opacuin folidum amorpHum, erofo - cavernofum,
ponderofiffimum; extremitatibus obfcure transparens; textura interna
non lamellata, fed aquabili, impalpabili, fraftura vitrata, nitente ;
fuperficie fua (ex parte) in ochratn plumbi pulverulentam nigram abiens; ad
flammam fiftulas ferruminatoriae ftrepitando diffiliens, turn illico colore lithar-
gyrii rubro obducendum, donee continuata flammas aftione de fe in plumbi
regulum abeat. Infidet huic nigro, plumbum fpatofum album, five verius
hyalino - cinerafcens , diaphanum cryftallinum, cryftallis parvis, inordinate:
polyedris, ftipatiffime accumulatis. Turn plumbum fpatofum flavum .crufta-
eeum, crufta quartam lines partem alta, per fuperfi'eiem plumbi fpatofi nigri
late difTufa, extus drufico - cryftallina; cryftallis partim inordinate polye-
C d r is ,