explanation op plates 415 



Explanation op Plates 

 Plate 2. — Photomicrographs of Meteorites 



Figure 1. — Photomicrograph from a thin-section of the Selma, Alabama, stone, 

 showing fragmental chondrules of several distinct types which 

 plainly are not due to simple crushing in place, but foreign to 

 their present environment. 



Figure 2. — Porphyritic chondrule with glass base from the tuffaceous {Cc) 

 chondrite of Tennasilm, Russia. 



Figure 3. — Photomicrograph of thin-section of the crystalline spherulitic 

 chondrite (Cck) from Bluff, Texas. Its original tuffaceous na- 

 ture is made evident by the presence of abundant fragmental 

 and distorted chondrules. 



Figure 4. — Photomicrograph of porphyritic chondrule in Heudersonville, North 

 Carolina, stone — a crystalline spherulitic chondrite, showing the 

 finely crystalline granular nature of the ground. 



Figure 5. — Photomicrograph from thin-section of the Renazzo, Italy, stone — a 

 black chondrite, showing the gradual merging into the general 

 ground-mass of a radiating enstatite chondrule. 



Plate 3. — Photomicrographs of Meteorites 



Figure 1. — Photomicrograph from a thin-section of the Estacado, Texas, 



stone — a crystalline chondrite, showing crystalline ground-mass 



and irregular and distorted form of chondrules. 

 Figure 2. — Photomicrograph from thin-section of Ensisheim stone — a black 



chondrite, showing a porphyritic chondrule gradually merging 



into the genei-al ground-mass and with finely granular material 



in the interstices of the phenocrysts. 

 Figure 3. — Photomicrograph from thin-section of the Colby, Wisconsin, stone — 



a white chondrite, showing the abundant maskelynite and its 



wholly unshattered condition. 

 Figure 4. — The calcium phosphate (merrillite) in the New Concord, Ohio, 



stone. 

 Figure 5. — Photomicrograph from a thin-section of the Estherville, Iowa, 



meteorite — mesosiderite, showing in the center a large, partially 



refused feldspar. 



Plate 4. — Photomicrographs of Meteorites 



Figure 1. — Photomicrograph from thin-section of the Knyahinya stone — a 

 gray chondrite, showing a porphyritic chondrule, with border 

 sometimes referred to as "glass," but apparently a secondary 

 product due to metamorphism. 



Figure 2. — Porphyritic chondrule — Parnallee stone — a gray chondrite, show- 

 ing the secondary "glass" border. 



