Latite
Intermediate, typically alkali-bearing volcanic rock with broadly comparable alkali feldspar and plagioclase; modern TAS names require chemistry.
Language and route: English scientific formation latite ← Latin place name Latium. English latite (1898) ← Latin toponym Latium
Literal gloss: rock named after Latium
The name and its history
Frederick Leslie Ransome (explicit 1898 naming proposal) · May 1898, American Journal of Science 5(29), pp. 355, 372 (directly checked); parallel USGS Bulletin 89 (1898)
- What does the word literally mean?
- Ransome formed the rock name latite from the Latin toponym Latium (Latia), an Italian province; the naming referent is geographical, not an original rock property.
- What did the original author mean?
- Ransome introduced latite for California Sierra Nevada lavas chemically intermediate between typical andesites and trachytes; he chose Latium because Italian analogues had been described.
- Why was the name needed?
- There was no satisfactory general name for the diverse effusive equivalents of monzonite: existing Italian subgroup names were too narrow for the Californian lavas.
- What evidence supported the original concept?
- Ransome mapped Stanislaus River lava flows (1895–96), compared alkali-rich chemical analyses and petrographic mineral proportions, and considered Washington’s Italian rock descriptions.
- How has geology changed the concept?
- Modern IUGS usage defines latite by composition and feldspar relations; the name is no longer a general field label for every trachyte–andesite intermediate.
Further historical context
Ransome introduced latite for California Sierra Nevada lavas chemically intermediate between typical andesites and trachytes; he chose Latium because Italian analogues had been described.
There was no satisfactory general name for the diverse effusive equivalents of monzonite: existing Italian subgroup names were too narrow for the Californian lavas.
Ransome mapped Stanislaus River lava flows (1895–96), compared alkali-rich chemical analyses and petrographic mineral proportions, and considered Washington’s Italian rock descriptions.
Modern IUGS usage defines latite by composition and feldspar relations; the name is no longer a general field label for every trachyte–andesite intermediate.
Editorial qualification
Ransome’s 1898 naming proposal was checked in the May issue, printed pp. 355 and 372; this verifies his stated motive, not a global absence of any earlier independent use. USGS Bulletin 89 is a companion version and its relative publication sequence has not been established.
Related names
Sources
- F. L. Ransome (May 1898), Some Lava Flows of the Western Slope of the Sierra Nevada, California, original proposal pp. 355 and 372 — Original naming proposal, directly inspected at printed pp. 355 and 372
- Mindat, Latite historical name record — 1898 Ransome attribution and Latium locality; primary work pending
- British Geological Survey, Rock Classification Scheme — Authority for modern rock categories and distinctions
- IUGS Subcommission / Le Bas et al. (1984), TAS classification of volcanic rocks — Modern chemistry-based classification and historical standardisation; not proof of each original coinage
- USGS Bulletin 89 (1898), extended report by Ransome — Parallel fuller study; do not assume issue sequence