Arizona weekly enterprise., 1890-12-06
NEW WONDERS.
Professor Hanks Discovers Magnetic Rocks ;G Arizona,--Experine with Speeimens---A New Field
 ofInqJiry.

The $. F. Bulletin gives the following which will be of interest to Arizonans. It is in reference to the last meeting of the San Francisco microscopical society:
 The society listened to q very interest ing paper read by Henry G. Hanks on some magnetic rocks discovered by him. self near Tucson. A. T., few days ago. On ascending ''Sentinel Hill,' near that town, partly with view of studying the geological formation and partly to obtain a satisfactory sight of the Santa Cruz Valley, he found the summit literally GOV cred with large, angular, and sub angular fragments of darker colOred cellular rock. fragments of which, when struck, gave the ringing sound characteristic of phon- olite The study of these rocks is very interesting. The lighter gray variety. revealed at the stone quarry. partakes somewhat of the character of the sOcalled white lava" of California. The sharp, high summits of these hills are basaltlike cellular, and of a darker color; but close observation of the rocks show them to be the. same, either changed, formed, or elected under different conditions. The Santa Cruz Valley is probably largely composed of these rocks disintegrated. There is no sign of aqueous deposition, but continued observation makes an igneous origin more doubtful
 A short distance from the summit was noticed what seemed to be slate but closer examination showed the rock to be the same, but rendered slaty by pressure The air-cells were elongated in a direc- ton at right angles with the pressure, which would indicate that the rock must have been plastic. At the risk of being Mr. esoil na ,47lI 1.5,, his doubts as to the igneous or even plu- tonic origin of these rocks, although he believed they would be generally so classed. Until he had some new evi- dence to the contrary, he should believe them to be metamorphic sediments A detailed dissertation on the Pathological character of these rocks would have been ] foreign to the purpose of the paper, which was to call attention to their polar mag netism.
 | On the following day, while examining | the basaltic fragments, Mr. Hanks held one of the largest to the needle of his compass, and he was much surprised 10 see 1t repslled instead Of attracted by 1t. i Realizing instantly that he held a natur- al magnet, he reversed the specimen and
 saw the needle strongly attracted
 These unexpected results led to a crit
 cal examination Of the mineral 1t was
 not magnetic. but genuine rock speci- men resembling basait. A polar basalt
 being new,i on his return to this city he
 began thorough reference to authorities
 but failed to find any aiiusion to such c
 property in basalt or any similar rock.
 Spallanizani. in d description of his as
 cent of AStna. mentions black scoriace
 ous lava, the dust of which "copiously
 adhered to the point of a magnetic knife
 and small pieces put the magnetic needle
 in motion at the distance of two lines
 If these rocks were polar, like those o
 Sentinel Hill, he did not discover 1t.
 Iron is plentiful in the basalts of Dis
 co Island, on the western coast of Green land. but no information Is accessible o its being formed into bands possessin. } polarity, which may be the cause ofthl remarkable properties noticed in the Tue son rock When this polarity was thu l discovered, q crucial experiment mas mad by Mir. Hanks. The large piece exhibitet l last evening was floated in an evaporat l ing dish placed in a large one filled wit 2 water; after several hours the magnet : poles of the rock fragment had moved { g coincide with the magnetic meridian c @ the earth, ill obedience to the subtle, ir l visible spirit that turks among the ston g particles.
 r A remarkable meteorite was foun e many years ago twenty miles from Tu( | son and eight miles from the road 1 y Tubac. United States Commissions l. Bartlett who visited Tucson in July, 1S5z l. saw 1t in a blacksmith shop used as " anvil. ltwas of metallic iron weighiu
 about six hundred pounds Bartlett VI