Kramer (Boron)
California, Mojave Desert, Kern County (Boron), United States
OtherB
- Type
- Zoned lacustrine borates (borax core, ulexite margin)
Middle Miocene lacustrine borate deposit (shale member of the Kramer beds, on the Saddleback basalt), mined by open pit at Boron: borax core (24.9 m sodium facies in drill hole MD-636), ulexite intermediate zone and discontinuous colemanite margin; boron and sodium supplied by hot springs according to the authors. Swihart et al. (1996): borax from +0.1 to +1.7 ‰ in ore-rich zones, from -5.1 to +2.3 ‰ in the clay-rich B interval (pH changes and Rayleigh effect during partial desiccation); cottonball ulexite from -5.5 to -4.6 ‰ above the borax and at -2.1 ‰ below, colemanite at -8.6 ‰; borax deposition spread over about 50,000 to 70,000 years. Indicative coordinates of the Boron open pit, not published in the article.
δ11B in ‰ (per mil) Values of the same system
Standard : NIST SRM 951
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| 1.1 ± 0.5 ‰ | 0.1 / 1.7 ‰ | 7 | borax of the A, Middle Ore and Lower Ore zones (sodium facies) Mean and standard deviation recalculated from 7 analyses, +0.1 to +1.7 (125,3 m +1.7; 128,6 m +0.1; 131,1 m +1.5; 137,2 m +1.0; 139,3 m +1.4; 148,7 m cœur +0.8; 148,7 m intérieur +1.0). Stable composition: lake source waters almost constant in δ11B during deposition. | Swihart et al. (1996), A boron isotopic study of a mineralogically zoned lacustrine borat… |
| −1.1 ± 2.7 ‰ | −5.1 / 2.3 ‰ | 7 | borax of the clay-rich B interval and top of the Lower Ore Mean and standard deviation recalculated from 7 analyses, -5.1 to +2.3 (142,3 m -3.4; 144,5 m a cœur -5.1; 144,5 m a +1.6; 144,5 m a -2.1; 144,5 m b +0.3; 144,5 m c +2.3; 146,0 m -1.2). Crystal "a" at 144.5 m varies from -5.1 to +1.6 ‰ from core outward, over a few weeks according to the authors (probably daily growth layers). | Swihart et al. (1996), A boron isotopic study of a mineralogically zoned lacustrine borat… |
| −5.1 ± 0.5 ‰ | −5.5 / −4.6 ‰ | 3 | cottonball ulexite, upper zone Mean and standard deviation recalculated from 3 analyses, -5.5 to -4.6 (121,8 m -5.5; 123,4 m -4.6; 124,4 m -5.1). Ulexite grown in lake-margin muds (mixing of sodium brine and calcium groundwater). Observed borax-ulexite offset of 6.0 ‰ at the top of the sodium facies, against 1.9 ‰ calculated at equilibrium. | Swihart et al. (1996), A boron isotopic study of a mineralogically zoned lacustrine borat… |
| −8.5 ‰ | 1 | massive ulexite ("television rock"), upper zone Single analysis (118,7 m). Cross-cutting vein ulexite, apparently not in equilibrium with the nearby colemanite. | Swihart et al. (1996), A boron isotopic study of a mineralogically zoned lacustrine borat… | |
| −2.1 ‰ | −2.1 / −2.1 ‰ | 2 | cottonball ulexite, lower zone Mean and standard deviation recalculated from 2 analyses, -2.1 to -2.1 (150,9 m -2.1; 156,1 m -2.1). | Swihart et al. (1996), A boron isotopic study of a mineralogically zoned lacustrine borat… |
| −8.6 ‰ | 1 | colemanite (several crystals), top of the upper ulexite zone Single analysis (118,7 m). Secondary colemanite formed by alteration of cottonball ulexite according to the authors (ulexite-colemanite offset of 3.0 ‰). | Swihart et al. (1996), A boron isotopic study of a mineralogically zoned lacustrine borat… | |
| 2.3 ‰ | 1 | borax Single analysis. | Oi et al. (1989), Boron isotopic compositions of some boron minerals, Geochimica et Cosmo… | |
| 0.6 ‰ | 1 | kernite Single analysis. Diagenetic product of borax, same BO3 + BO4 configuration. | Oi et al. (1989), Boron isotopic compositions of some boron minerals, Geochimica et Cosmo… | |
| −3.1 ‰ | 1 | ulexite Single analysis. Theoretical value of -10.3 ‰ if the solution holds only B(OH)3; agreement requires a B(OH)3 mole fraction of 0.62, i.e. a pH of about 8.6. | Oi et al. (1989), Boron isotopic compositions of some boron minerals, Geochimica et Cosmo… | |
| −12.8 ‰ | 1 | colemanite Single analysis. Diagenetic product of inyoite; inyoite calculated at -11.7 ‰ at 25 °C for a +1.1 ‰ solution dominated by B(OH)3 (pH below about 6.5). | Oi et al. (1989), Boron isotopic compositions of some boron minerals, Geochimica et Cosmo… |
Deposits of the same type
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- Smackover Formation brines (East Texas) United States
- Haynesville Shale produced water United States
- Webster-Addie (Democrat) United States
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Cite this page
IsoFind Atlas (2026). Kramer (Boron), isotope signatures. https://www.isofind.tech/isotopes/en/deposits/kramer-boron/ (accessed 2026-10-19).
@misc{isofind2026kramerboronisotopesignatures,
title = {Kramer (Boron), isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/kramer-boron/},
note = {Accessed 2026-10-19}
}Updated : 2026-10-19