Page:A Treatise on Geology, volume 2.djvu/189

 CHAP. VIII. contains lead glance, very rich in silver; black blende, small granular; common iron and liver pyrites; a little arsenical pyrites. Dark red silver ore, brittle silver ore, white silver glance, and plumose antimony ore also occur. The veinstones are principally quartz, much brown spar, and calc spar. There is a difference of situation in the rein, characteristic of these substances; quartz is generally on the outside. The veins are from 2 feet to 10 inches wide, and are south and south-west veins.

The third deposit yields lead glance, with but little silver. Its contents are lead glance, with nearly an ounce of silver to the quintal; much iron pyrites; some black blende; a little red iron ochre. The veinsstones are quartz; sometimes also chlorite, mixed and surrounded with clay. These are all northern veins.

The fourth deposit is also composed of lead glance, with but little silver (from a quarter to three quarters of an ounce of silver to the quintal). Besides the lead ore, there is radiated pyrites, and sometimes a small quantity of brown blende. The veinstones are very distinct, and consist of heavy spar, fluor spar, a little quartz, and rarely calcareous spar. The veins are from 1 foot to a fathom in width, and have generally a western direction.

(To this vein system, Werner refers many deposits beyond the Saxon districts, not hesitating to include the Derbyshire mines, which certainly offer several interesting analogies as to the veinstones, the direction, and contents of the veins.)

The fifth deposit contains native silver, silver glance, and glance cobalt, besides a small portion of grey copper ore; lead glance rich in silver; a little brown blende; and sparry ironstone. The veinstones are disintegrated heavy spar, and blue fluor. It always occurs at the intersection of the southern and western veins (or first and fourth vein systems here described), or in the middle of the western veins.

The sixth deposit consists of native arsenic and red