Iron_ and _Titanium_, with a little _Potass_. Some of which ingredients were no doubt derived from the _gangue_ with which the metallic substance is intimately mixed. This is a discovery no less curious than important, and would seem to point out the origin of the _Menachanite_, in which _Titanium_ was first discovered by Mr. Gregor. The great mass of _Serpentine_ ends at _Coverack Cove_, a spot which well deserves the attention of the Geologist, as offering a series of rocks of a very mixed character; these consist of green and reddish-brown _Serpentine_, with the _Jade_ of Saussure, (the _feldspath tenace_ of Haüy) and _Diallage_[133] of the green and metalloïde varieties; some of the _Felspar_ found here is of a violet colour, and is striated like that of Labrador. In beds which lie below high-water mark in this Cove the mineralogist may obtain masses of _Diallage Metalloïde_, six or eight inches in length.[134] A beautiful rock succeeds and continues for three miles along the coast to the _Manacles_; and in the interior of the country it predominates through the greater part of the parish of _Saint Keverne_. It has _compact Felspar_ for its base, in which are imbedded crystals both of _Diallage_ and _Hornblende_. In the proportion, as well as the magnitude of these constituents, says Mr. Professor Sedgwick, there is such an unusual variety, that we were almost led to conjecture, that during the deposition of the mass many conflicting principles had been in action, not one of which was long able to keep the mastery over the others; there are for instance many large blocks which in one part resemble a fine _Greenstone_, and in another, a coarse porphyritic _Diallage Rock_; within the distance of a few feet these varieties may be observed to alternate repeatedly, sometimes in the form of stripes, but more frequently in amorphous concretions separated from each other by lines which are perfectly defined. _Schistose Greenstone_ occurs again at _Porthowstock_, and a small bed of _Serpentine_, on the south-west side of _Porthallo_ in the cliff, which rests on a reddish _Talc_ which lies, as before, on _Clay-slate_. No other variety is observable from hence to the Helford River, except in the appearance of a _Pudding Stone_, or _Conglomerate_, near the _Dennis Creek_, composed of rounded fragments of Slate in which veins of _Quartz_ are distinctly visible. The traveller will not fail to visit the stream of _Tregonwell Mill_,[135] near the village of _Menacchan_, celebrated as the habitat of the _Titaniferous Iron_ (_Menacchanite_, or _Gregorite_) discovered by the late celebrated Mr. William Gregor.[136] He will also receive much gratification by extending his route to _Mawnan_ Cliffs, where he will observe a most extraordinary intermixture of fine and coarse grained (_Grawacke?_) slate, which are traversed by many contemporaneous veins, some composed of _Quartz_, and others of _Ferriferous_ _Carbonate of Lime_; some small cavities are coated