SUMMAET. 465 



serpentine may also be seen in a very striking manner. Serpentinization 

 takes place from cracks in the sandstone just as it does in olivines, excepting 

 for the difference of scale. The meshes of the net in sandstone croppings 

 are often about a foot across, while those in olivine are microscopic. 



The ore deposits occur at half a dozen points in the district, all of 

 them near the basalt area, which is as nearly as possible in the center of 

 the group of ore bodies. Ore is stated on good authority to have been 

 found also in the Lake claim, at the contact of a basalt dike with the in- 

 closing metamorphic rocks. Many mineral springs exist around the basalt 

 area close to the mines and some of them carry borax. Solfataric gases 

 still issue in small quantities at one point iu the Redington mine and the 

 upper portions of the ore deposits are of such a character as to indicate 

 that they were deposited near an original surface. All of these facts indi- 

 cate that the deposits are indirectly due to the basalt eruption and that the 

 nature of the process was similar to that at Sulphur Bank. 



The upper part of tlie famous Redington mine was an extremely rich 

 bonanza of great size and irregular form. It carried much metacinnaba- 

 rite. Leading up to this mass from below were three regular fissures, and 

 two of them Avere filled with ore, forming well defined fissure veins. This 

 is particularly interesting as a proof that true, simple fissure veins maybe 

 formed by hot solfataric springs, which has been doubted by some geol- 

 ogists. 



The California or Reed mine, the ^lanhattan, the Lake, the Andalusia, 

 and several prospects, as well as the Redington, lie in this district, but of 

 late years only the last has been worked. Metacinnabarite was the princi- 

 pal ore of the California Stibnite occurs on the Lake and JIanhattan 

 claims and is said to have been found in contact with cinnabar. 



Neu idria. — Thc Ncw Idria mining district lies among some of the highest 

 peaks of the Coast Ranges, at the southern end of the IMt. Diablo Range. 

 The views are very extensive and the scenery is i)icturesque, but it is iu part 

 very forbidding, the portion of the Coast Ranges lying to the nortlieast of 

 the district being a mountainous desert. 



11ie higher j)ortion of the Jit. Diablo Range is here, as for the greater 

 part of it.s length, composed of highly metamorphosed rocks of the Knox- 



MON XIII 30 



