There is not much Limestone on the Quantocks, and caves are a rarity. At this spot an outlier of Carboniferous Limestone lies in close contact with beds of Greywacke Slate--a very unusual conjunction, which prepared us for something new and strange in the way of crystallisations. Descending a few yards beyond the entrance, the main passage rises a little, and then drops gradually towards a stagnant pool, beyond which it is impossible to get. The length of this portion is only 140 feet, and the direction from north-east to south-west. Certain narrow passages, however, bore into the Limestone on the north, and extend their ramifications much farther. Only one of these seems to have been known before our visit. In the main passage, near the pool, is seen the special wonder of Holwell Cave, a brilliant display of arragonite crystals all over the roof. Arragonite usually occurs in massive deposits of satin spar, distinguished by a perfection of whiteness when newly split, a whiteness that grows dingy very soon if you try to keep specimens. Here it occurs in quite another form--the coralloid, known as flos ferri; thousands of filaments or spicules ramifying from centres, and looking as soft as cobweb, though as brittle as blown glass. This delicate product is often tinged with a pink stain like that of fluor-spar. Andrew Crosse, the electrician, who was carrying on his researches in the neighbourhood when Holwell Cavern was found about 1800, thought that the crystal might have been distorted by slow degrees into these fanciful shapes "through the invisible action of electric energy," an agent to which most mysterious natural processes have been attributed some time or another; but the fibrous arragonite, scientists tell us, is by no means abnormal. It all lies on the Greywacke part of the roof; the adjoining Limestone has no arragonite, but is incrusted with the usual sheets and bosses of calcite, mutilated somewhat by visitors who have taken away mementos. "Ain't it ornamental, sur?" said our conductor; but his exclamations were still more enthusiastic when the magnesium ribbon lit up the millions of arragonite crystals that covered the roof with a glistering efflorescence. Then the flashlight blazed out, as our camera got into action, and the old man was speechless with amazement. He had known the cave, boy and man, all his life, but never before had he, or anyone else for that matter, gazed upon all its beauties. Several photographs were secured--among them the portrait of a sleeping bat clinging to the groining of calcite--and then the cave grew too smoky for further work. So we went off to explore.