64 MISS C. A. EAISIN ON CEKTAIN [Feb. I90I, 



which forms a streak in the band and contains blackish plates of 

 ilmenite or haematite, with rather abundant small epidote(?). 



A few yards away, where the cliff nearly reaches the road, is a 

 second nodular mass of rounded outline about 2 feet across (fig. 2, 

 p. 63). The rock here is grey, banded, finely laminated, sometimes 

 showing current-bedding. The laminae can be traced up to the sides 

 of the nodule, and even into it (seen in thin slices), while above it 

 they are slightly faulted and displaced, with a number of quartz- veins, 

 all more or less wedge-shaped and pointing downward. At a 

 lower level, and a few feet in front, are a banded indurated grit 

 and a little slate. The margin of the nodule is blackish, weathering 

 to slate-colour ; it is crowded with crystals, steel-like when fresh, 

 brown when weathered, and contains scattered reddish garnets, 

 about 1 mm. in diameter. The mass of the nodule is similar, jointed 



Fig. 3. — Part of a slice for the microscope (x40) taken from, tlie 

 nodule (hy the road to Longwilly) shown in jig. 2, p. 63. 



[A garnet and a small imperfect crystal of ' ottrelite ' are seen embedded in a 

 carbonaceous groundmass. The garnet is mostly sbarp-edged, with regu- 

 larly arranged inclusions along cry stall ographic planes.] 



somewhat rhomboidally, is firmer towards the exterior, but in the 

 centre becomes dusty, crumbles away from around the small 

 garnets,^ and blackens the fingers when rubbed. 



The marginal zone is seen under the microscope to consist 

 of a mosaic with carbon-dust, and with curving sheaves of the 

 supposed ottrelite. These, although apparently continuous, are 

 really crowded with enclosed grains of the groundmass. In the 

 next zone garnets appear, generally with a border of opacite (fig. 3)^ 



1 See A. Renard, Bull. Mus. Roy. Hist. Nat. Belg. vol. i (1882) p. 9. 



