MINERALOGY. 



539 



Horn- 

 blende, 

 late. 



horn. 

 blende. 



Orjrctogno- Geo<ntostic Situation It occurs in great abundance in 

 y- primitive rocks, and also in some rocks of the secondary 

 ^ ~<~"* class. 



Geographic Situation. It occurs very abundantly in 

 Scotland, in greenstone and syenite : and imbedded in 

 limestone, gneiss, and mica-slate. It is found in simi- 

 lar rocks in England ; and plentifully in the primitive 

 trap- rocks of Ireland. 



Second Kind. HORNBLENDE-SLATE, Jameson. 

 Hornblende Schiefer, Werner. 



External Characters. Colour green. Occurs massive, 

 and in thin promiscuous prismatic concretions. Inter- 

 nally glistening, passing into shining and pearly. Frac- 

 ture straight slaty. Opaque. Yields a greenish-grey 

 coloured streak. 



Geognostic Situation. It occurs in beds, in granite, 

 -, mica-slate, quartz-rock, sometimes also in clay- 

 slate, and frequently along with beds of primitive lime- 

 stone. 



Geographic Situations. In Scotland, it occurs in 

 gtieiss. in the districts of Braemar and Aberdeen, in 

 Aberdeenshire ; in Banffshire, as near Portsoy ; in Ar- 

 gyleshire, as in the islands of Coll, Tirce, &c. ; in In- 

 vcmess-shire, as in the islands Rona, Lewis, &c. ; and 

 in many other part* in Scotland ; and also in England 

 and Ireland. 



Third Kind. BASALTIC HORNBLENDE, Jameson. 

 Baaaltische Hornblende, Werner. 



External Chnracteri. Colour black. Occurs crys- 

 tallized, in six-sided prisms, variously modified. Lustre 

 of cleavage splendent and vitreous, approaching to 

 pearly ; that of the cross fracture glistening. Frac- 

 ture small-grained uneven, approaching to conchcidal. 

 Opaque. Rather harder than cuimnon hornblende. Af- 

 fords a dark greyish-white streak. 



Geogmatic and Geographic Situation. It occurs 

 imbedded in trap-rocks in Scotland, and other coun- 

 tries. 



THIRD SUBSPECIES. 

 ACT\ SOLITE, Jameson. Strahlstein, Werner. 



This ul>-pecies it divided into three kinds, viz. As- 

 bestous Actynolite, Common Actyuolite, and Glassy 

 Actynolite. 



First Kind. ABESTOt's AcTYNOLlTE, Jamcton. 

 Asbeslartiger Strahlstein, Werner. 



mill Characters. Colours grey, green, blue, 

 and brow n. Occurs massive, in distinct concretions, 

 which are fibrous, and sometime* collected into others 

 which are wedge-shaped and granular. Rarely occurs 

 crystallized, in delicate capillary, rigid, moss-like, su- 

 perimposed crystals. Internally the lustre is glisten- 

 ing and pearly. Opaque, or slightly translucent on 

 the edges. Fibres or concretions in groups are soft, 

 but individually equally hard with the other varieties 

 of actynolite. 



Geozitijitic Situation. It occurs in beds in gneiss, 

 mica-slate, and granular limestone. 



Geographic Situation. In Scotland, also in Norway, 

 Sweden, &c. 



>'id Kind. COMMON ACTVNOLITE, Jameson 



:ier Stralil-tcin, Werner. 



External Characters. Colour green. Occurs mas- 

 sive and disseminated ; also in wedge-shaped prismatic 

 concretions, which are scopiform, stellular, and pro- 

 miscuous ; these sometimes pass into angulo-granultr 

 concretions. Frequently the pri ,matic concretions are 

 collected into large granular concretions. Internally 

 shining, inclining to glistening, and pearly inclining 

 to vitreous. Fracture uneven and conchoidal. Ge- 

 nerally translucent on the edges. 



gnostic Situation. It occurs in beds in gneiss, 

 mica-slate, and talc-slate. 



Actjrnolite. 



Atbecuxu 

 ctyoolite. 



I mnv n 

 aciynolile. 



Geographic Situation. It occurs at Eilan Reach in Oryetogno- 

 Glenelg, in Inverness-shire ; near Fortrose in Cromar- ,_^'__-. 

 ty ; in the parish of Sleat, in the isle of Skye ; ditferent 

 places in the isle of Lewis. 



Third Kind GLASSY ACTYNOLITE, Jameson. Gla- Glassy ac- 



sartiger Strahlstein, Werner. tynolite. 



Exttrnal Characters. Colour green. Occurs mas- 

 sive : also in prismatic distinct concretions, which 

 are fibrous, or radiated, arranged in a scopiform, and 

 rarely in a promiscuous manner ; and these are again 

 collected into wedge-shaped prismatic or granular con- 

 cretions. Internally shining, sometimes splendent, and 

 intermediate between vitreous and pearly. Trr.nslu- 

 cent or semi-transparent. Brittle. Uncommonly easily 

 frangible. Traversed by numerous parallel rents. 



nostic and Geographic Situations. It occurs in 

 primitive rocks in the isle of Skye, and other parts of 

 Scotland. 



FOURTH SUBSPECIES. 



TREMOLITE, Jameson. Tremolith, Werner. Tremolite. 



This subspecies is divided into three kinds, viz. As- 

 bestous Tremolite, Common Tremolite, and Glassy 

 Tremolite. 



First Kind* ASBESTOUS THEMOLITE, Jameson. Asbcstom 



Asbestartiger Tremolit, Werner. tremolite. 



External Characters Most common colour grey- 

 ish-white; it is also yellowish- white, greenish-white, 

 rarely reddish-white, and pale violet-blue. Occurs 

 massive ; also in fibrous or very thin prismatic distiiu-t 

 concretions. Internally shining, approaching to glist- 

 ening, and pearly. Translucent on the edges. Rnther 

 easily frangible. 



Ger.gno tic Situation It occurs most frequently in 

 granular foliated limestone, or in dolomite ; sometimes 

 in chlorite ; and more rarely in secondary trap-rocks. 



Geographic Silualinn. It occurs in foliated granular 

 limestone in Glen Tilt, in Perthshire, and in Glen Elg 

 in Inverness-shire ; in dolomite in Abcrdeenshire and 

 Icolmkill; in the Shetland Islands ; and in basalt in the 

 Castle Rock of Edinburgh. 



Second Kind. COMMON TREMOLITE, Jameson Ge- Common 

 mciner Trtuiolit, Werner. trcmolite. 



External Characters. Most frequent colour white, sel- 

 dom grey, pale asparagus-green, and blue. Occurs mas- 

 sive ; also in distinct concretions, which are prismatic, 

 and these are collected into longish granular concretions. 

 Sometimes crystallized in oblique four-sided prisms. 

 Lustre shining, and intermediate between vitreous and 

 pearly. Fracture uneven or corc-hoiiltl. Translucent 

 or semi-transparent, Rather brittle. Easily frangible. 

 Powder rough to the feel. 



Geognostic Situation. Like the asbcstous subspecies, 

 occurs principally in granular limestone, or dolomite, 

 and in metalliferous ! 



Geographic Situation. It occurs in Glen Tilt, Glen 

 Elg, and in the Shetland Islands ; also at Clicker Tor 

 in Cornwall. 



Third Kind. GLASSY TREMOLITE, Jameson. Gla- GUsty ire- 

 sartiger Tremolith, Werner. molite. 



External Characters. Colour white. Occurs mas- 

 sive ; also in distinct concretions, which are straight 

 and scopiform prismatic, with numerous cross- 

 rents, and these are again grouped into thick and 

 wedge-shaped concretions. Frequently crystallized in 

 long acicular crystals. Lustre shining, but in a lower 

 degree than the preceding subspecies, and'intermediate 

 between vitreous and pearly. Translucent. 



Geognostic Situation. It is the same as that of the 

 preceding subspecies, occurring principally along with 

 granular limestone. 



Geographic Situation. In Scotland it occurs along 

 with the other kinds. 



