60 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxxii. 



with an ordinary boulder, where it lay ainono- the weeds until its true 

 nature was surmised by Mr. Coleman. 



As described by Mr. Gilbert in a letter to the writer, the stone at 

 first sight is "a completely formless pol3^hedral block, but on longei- 

 inspection it resolves itself into something of a characteristic aerolite 

 form — a blunt quadrangular pyramid with smooth, unpitted faces and 

 rounded edges.'' (See Plate VI.) The thickness of the block he gives 

 as 35.56 centimeters, the l)asal edges measuring, respectively, 35.56, 

 43.18, and 50.8 centimeters. The blunt apex of the pyramid — evi- 

 dently the front side during flight — was covered for a distance of about 

 15.24 centimeters with a thin coating of carbonate of lime, which 

 presumal)ly marked the depth to which the stone penetrated on first 

 striking the ground. This portion of the stone is smooth, except for 

 the lime coating, and shows, as do the sides, the original though now 

 oxidized crust. The base is, however, rough, with a somewhat scaly 

 brown-black appearance, quite unlike the rest of the surface, and is 

 divided by numerous fissures, due to weathering, as shown in fig. 3 of 

 Plate VI. "The whole appearance," writes Mr. Gilbert, "indicates 

 that it represents what was once a fine, large, well-orientated aerolite, 

 man}^ of the characteristics of which have become obliterated through 

 exposure." 



Macroscopically the stone is dense, of a dark-grav color, and suffi- 

 ciently compact to receive a good polish. Cut surfaces show abundant 

 "kugel" chondrules of all sizes up to 3 millimeters in diameter, 

 though forms above 1.5 to 2 millimeters are rare. These are so firmly 

 embedded as for the most part to break with the stone. The metallic 

 portion is quite inconspicuous to the unaided eye. 



Under the microscope in thin sections the stone is seen to be com- 

 posed of extremely variable chondrules, often fragmental, and scat- 

 tered particles of silicate minerals embedded in a dark opaque ground 

 which, by reflected light, shows up as a network of deep-blue metallic 

 iron and its oxidation products and brilliant points of yellow-white 

 troilite. Olivine, enstatite, and a monoclinic pyroxene constitute the 

 silicate portion. These are, in large part, in the form of fragmental 

 chondrules, though sometimes quite perfectly oval. (Plate VII, fig. 1.) 

 The olivine chondrules show the common barred and porphyritic 

 forms, the latter with a more or less glass}^ or fibrous base. (Plate VII, 

 fig. 2.) Some of them are mere aggregates of polarizing points with- 

 out evident interstitial matter. There are also occasional large, scat- 

 tered, single crystals and fragments not constituting chondrules. 

 The enstatites occur under similar conditions and also in fan-shaped 

 radiating forms, very much broken and otherwise imperfect (Plate VII, 

 fig. 1), and in dense crj^pto-crystalline forms, presenting no opportunity 

 for optical determination. (Plate VII, fig. 3.) The monoclinic pyr- 

 oxenes are the least abundant of the silicates and show the usual (in 



