518 



MINERALOGY 



Oryctogno- Geognostic and Geographic Situations. The princi- 



7- 



Di-prisma- 

 tic Olivc- 

 nite, or 

 Lenticular 

 Copper. 



pal locality of this rare mineral is Virneberg, near 

 llheinbreitenbach, on the Rhine, where it occurs along 

 with quartz, calcedony, red copper-ore, and malachite, 

 in greywacke. 



II. DI-PRISMATIC OLIVENITE, on LENTICULAR COP- 

 PER, Jameson. Di-prismatischer Oliven-Malachit, 



Mohs. Linsenerz, Werner. 



Prism unknown. Cleavage in the direction of the 

 terminal and bevelling faces of an oblique four-sided 

 prism. Streak pale verdigris-green, and sky-blue. 

 Hardness = 2.5. Sp. gr. = 2.82.9- 



External Characters Colour sky-blue, which some- 

 times passes into verdigris-green. Scarcely occurs 

 massive, generally crystallized : 



1 . Very oblique four-sided prism, acutely bevelled 

 on the extremity, and the bevelling planes set on the 

 obtuse lateral edges. 2. Very flat, longish, rectangular 

 double four-sided pyramid, in which the lateral planes 

 of the one are set on the lateral planes of the other *. 



Crystals middle-sized and small, and sometimes crys- 

 tallized in druses. Externally smooth and shining ; 

 internally glistening and shining, and pearly, inclining 

 to vitreous. Fracture small-grained uneven, which 

 sometimes passes into imperfect conchoidal. Fragments 

 indeterminate angular, and rather sharp-edged. Trans- 

 lucent. Yields a pale verdigris-green, or sky-blue 

 coloured streak. Brittle, and uncommonly easily 

 frangible. 



Chemical Characters Before the blowpipe it is con- 

 verted into a black friable scoria. 



Constituent Parts Oxide of Copper, 49 



Arsenic Acid, . 14 

 Water, . . 3598 



Chenevix in Phil. Trans, for 1801. 



Geognostic and Geographic Situations It has been 

 hitherto found only in Cornwall, where it is associated 

 with copper-mica, and other cupreous minerals. 



III. ACICULAH OLIVENITE, Jameson Nadelformiger 

 Oliven-Malachit, Mohs. 



Prism unknown. Cleavage unknown. Streak olive- 

 green; brown. Hardness = 3.0. Sp. gr. 4.2 

 4.6. 



This species is subdivided into four subspecies, viz. 

 Radiated Acicukr Olivenite, Foliated Acicular Olive- 

 nite, Fibrous Acicular Olivenite, and Earthy Acicular 

 Olivenite. 



FIRST SUBSPECIES. 



Radiated RADIATED ACICULAR OLIVENITE, Jameson. Stra- 



Acicular hlerz, Werner. 



External Characters. -Externally colour dark ver- 

 digris-green, sometimes bordering on blackish-green ; 

 internally pale verdigris-green, either pure, or inter- 

 mixed with sky-blue. Occurs massive and flat reni- 

 form ; also in radiated prismatic concretions, which are 

 straight and scopiform ; and crystallized in flat oblique 

 four-sided prisms, acuminated with four planes. Crys- 

 tals generally small, and superimposed. External sur- 

 face of the reniform shape very drusy. Internally 

 lustre intermediate between shining and glistening, and 



Acicular 

 Olivenite. 



pearly. Fragments wedge-shaped. Translucent on Oryctogtio- 

 the edges. Brittle, and easily frangible. *J- 



SECOND SUBSPECIES. 



FOLIATED ACICULAR OLIVENITE, ,/amwcm. Blat- Foliated 

 triches Olivenerz, Werner. Acicular 



External Characters. Colour green. Seldom occurs 

 massive, and in angulo-granular concretions, generally 

 in drusy crusts, and in small crystals, which present 

 the following varieties of form : 



1. Oblique four-sided prism, acutely bevelled on the 

 extremities, the bevelling planes set on the acute late- 

 ral edges. 2. Preceding figure, in which the obtuse 

 lateral edges are more or less deeply truncated. 3. 

 Acute double four-sided pyramid; sometimes the angles 

 on the common base are flatly bevelled ; and the bevel- 

 ling planes are set on the lateral edges. 



Crystals small and very small, and always superim- 

 posed. Planes of the crystals smooth, shining, and 

 splendent. Internally glistening, and lustre resinous, 

 inclining to pearly. Fracture small and imperfect con- 

 choidal, which passes into uneven. Fragments inde- 

 terminate angular, and rather sharp-edged. Ranges 

 from translucent to translucent on the edges. Yields 

 an olive-green coloured streak. Rather brittle, and 

 easily frangible. 



Chemical Characters.- Before the blowpipe, it first 

 boils, and then gives a hard reddish-brown scoria. 



Constituent Parts. Oxide of Copper, 60.0 



Arsenic Acid, 89.7 99.7. 



Chenevix, Phil. Trans. 1801. 



Geognostic and Geographic Situationt. It has been 

 hitherto found only in the copper-mines of Cornwall. 



THIRD SUBSPECIES. 



FIBROUS ACICULAR OLIVENITE, Jamseon. Fasriges Fibrous 

 Olivenerz, Werner. Acicular 



External Characters. Colours green, yellow, brown, 

 and white. Colours sometimes arranged in curved 

 and striped delineations. Occurs massive, and reni- 

 form; in fibrous concretions, which are delicate, 

 straight, and scopiform, and these are collected into 

 coarse or small granular concretions, and sometimes 

 traversed by others, which are curved lamellar; also 

 crystallized in capillary and acicular oblique four-sided 

 prisms, in which the obtuse lateral edges are truncated, 

 and bevelled on the extremities, the bevelling planes 

 being set on the acute edges. Crystals small and very 

 small, and sometimes scopiformly aggregated. Inter- 

 nally the massive varieties are glistening or glimmer- 

 ing, with a pearly or silky lustre. Fragments inde. 

 terminate angular, and wedge-shaped. Opaque, seldom 

 translucent on the edges, and only translucent in the 

 crystals. Rather brittle. Fibres sometimes flexible f. 

 Streak brown or yellow. 



Constituent Parts. Oxide of Copper, 50 



Arsenic Acid, . 29 

 Water, . . 21100 



Chenevix, in Phil. Trans, for 1801. 

 Geognostic and Geographic Situations. It is asso- 

 ciated generally with the other arseniates of copper 



* The double four-sided pyramid is so flat that it has a lenticular aspect ; hence the name Lenticular Copper given to this species. 



J- The fibres are sometimes so delicate, so short, and so confusedly grouped together, that the whole appears like a dusty cottony mas*, 

 the true nature of which is discoverable only by the lens. At other times, this variety appears in thin lamins, rather flexible, sometimes 

 scarcely perceptible to the naked eye, sometimes tolerably large, and perfectly like Amianthus papyraceus. Sournon, Plvil. Trans, for 

 1801, part i. p. 180. 



