Arizona republican., 1913-11-10
MILLER TELLS OF
Continued from Page One.)

1 Nalue. To the ordinary man II would seem very simple to determine approximately the full cash value of any property or class of properties. 1 but to those who live in mining district the difficulty of determining
 the full cash value of a mine is soon realized.
 From the very nature of things, a mine being below the surface of 1 the ground cannot be seen in the same manner that a farm, or a busi- ness building, or residence in the i city can be looked at and it's value 1 determined by either the price at ! which it last changed hands or the l price at which adjoining similar property has been sold. As has been i very properly said in a legal deci- i sion in Colorado, the value of mine 1 is based on it's ore developed and undeveloped, seen and unseen, known and unknown. Here it should be stated that there are really two diff ferent definitions to the word mine" one being applied to q body of ore whether it is being wrought or not, and the other applying to the various underground openings which are used for the purpose of extracting ore. One may have an enorfous body of ore opened up with nothing but drill holes which might be of value, but yet near it might be another property with miles of underground openings | and with but a small amount of Ofe ] in sight. In this discussion, however. 1 both classes of property are included 1 in the word mine"
 i Going back to the Colorado legal definition that a mines value de- 1 bends upon the value of the ore both developed and undeveloped. it is easy l to see that in vein mining the value l of a property can never really be known until it's complete eXhaustion; not until the very last ton of ore l has been taken out and treated is the
 data available for the purpose of cal cuIating what the mine was worth before any of the ore was removed. In our own state, Arizona. there are no doubt hundreds and perhaps thou sands of ore deposits in which not single pick has been struck, nor a shaft sunk These ore deposits are of value, but how is it possible to know of their ore and to value them 1 until they have been discovered and l opened up
 In the early days of mining in the l United States, and in Arizona, the policy of putting large amounts of ore in reserve was not followed. If a rich vein outcropped, shaft was sunk upon it, and after it had gone | down 100 feet one began to take out 1 the ore and either ship it, or treat 1 it locally n d mill or a smeIter. The shaft might be kept perhaps 100 feet ahead of the extraction level, or the 1 levels from which the ore was being taken. and if perhaps the shaft sud ] denly went into Valueless material after sinking 100 or 200 feet the l property was irrlan likelihood aban- i doncd. Later on, in ma1lF of the cpp- 1 per mines of Arizona, large amounts | of water were encountered in going | down, and in many cases the rock I was soft and treacherous and after 1 being opened up would crush the ] timbers supporting the galleries. For 1 this reason development was not l pushed and many d mine had not l more htna one years ore in sight or l developed ahead of it's actual yearly i requirements. Most of these mines l were in the nature of Assures which stood either vertical or nearly so, so
 that the expense of development to 1 the very bottom of the mine was pro
 hibitive.
 Within the last few years however,
 
 1 state of Arizona several copper mines
 of what is known as the ''porphyry' | type. In these cases the ore occurs l in large masses. Wni'n roughly are 1 flat that S. they might extend thous- ands of feet north and south, east and 1 west and vet be only frof fifty to
 400 feet thick. They are covered with
 west. and yet be onir from fifty t1 even as high as 400 feet, which was ! entirely barren, and notwithstanding | this barren zone covered what is To-
 cally called a zone of secondary en- 1 richment. These ores were, relatively l speaking, Of low grade, running be- ! tween IF to 212 per cent in copper, | and therefore, in order to make them 1 commercially available they had to l be treated in large quantities. The old mines of Arizona often ran as high as 25 per cent copper and mauy
 of them today yield from to s per cent copper, not including the gold and silver also in the ore.
 Now before the capital could be in- duced to equip these porphTry mines with the huge plants necessary to treat from 5000 to 1000 tons day, 1t
 was necessary to develop and prove 1 a sufficient tonnage of ore to warrant i these enormous expenditures. The day has gone by when a mine could be started on q shoestring and pay for itself almost frof grass roots. The configuration of the porphyry mines with the ore lying roughly in a hori- 1 zontaI sheet was such that this prov ing could be readily done by churn drill holes and so the ground was
 laid out in checker board fashion, and
 at the corner of each 200 feet square drill hole was put down. The re-
 suit is today in Arizona we have at least four properties of this class,
 showing respectively 75.0O0,O0O. 45,-
 100000. 26,OOO,OOO and 20,0000O0 tons
 together with two others of similar
 nature with not great tonnages
 blocked out. though their possibilities
 are by no means exhausted.
 We also have in the state. four large