Bulletin Volume 3, PT. 1

Bulletin Volume 3, PT. 1

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 edition. Excerpt: ...at this time." As developed in the descriptions on pages 100 to 145, the rocks represented by the analyses in the table on page 147, and grouped under the field name nelsonite, are unique in composition and represent new and extreme ultrabasic igneous rock types. In composition they are all alike in containing apatite as one of the essential minerals. They are unlike as to rutile, ilmenite, or magnetite being the predominant dark ore mineral. The two types are represented by the analyses in columns IV and VIII of the table, the others being regarded more as gradational facies and therefore intermediate in composition between the two principal types. As shown in the summary above, all the analyses of nelsonites, except hornblende nelsonite and gabbro-nelsonite (not included in the table of analyses above, page 147), fall into class V (perfemane), but into subrang positions of rangs, sections, and orders not yet named. It is therefore proposed that new names be given to those varietal forms of nelsonite which fall within the limits of the classificatory scheme. The two analyses of hornblende nelsonite and the single analysis of gabbro-nelsonite are not included in the table of analyses on page 147, but are given under the separate descriptions of the two types on pages 135 and 140. The two analyses of hornblende nelsonite fall into class IV (dofemane) near class V (perfemane) but are classed as of IV. They occupy border positions in the classificatory scheme, hence it is thought best not to suggest a new name for them. The analysis of gabbro-nelsonite falls into class IV (dofemane) but into rang and subrang positions not yet named. The names roselandase and roselandose are proposed as appropriate rang and subrang names for this rock. Referring...
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Product details

  • Paperback | 126 pages
  • 189 x 246 x 7mm | 240g
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236505107
  • 9781236505101