Three Rivers Glass — Glass Colors

The Three Rivers Glass Company made its bottles and jars in essentially two colors: flint (colorless) and amber. That is what the period trade directory recorded, what the surviving marked ware shows, and what the standard history documents. No green, blue, cobalt, milk-glass, or deliberately-amethyst Three Rivers glass is attested. This article gives the evidence and clears up the recurring “aqua,” “green,” and “olive” misreadings.

The documented answer: flint and amber

The trade directory. The American Glass Review Glass Factory Yearbook recorded, in 1934, that Three Rivers’ products “were made in flint and amber” (AGR 1934:100), a listing amended to “flint packers, fruit jars, beverage bottles, proprietary ware” in 1936. Across every AGR entry from 1927 to 1936 — and throughout the heavily-cited Bottle Research Group chapter that reproduces them — no color other than flint and amber is ever named, for either the Texas plant or the Bastrop, Louisiana Plant. (“Flint” is the glass-trade term for colorless glass.)
The price list. Michael David Smith’s Texas Glass (1989) price list records colors on only the items where it mattered — and only ever as clear or amber (e.g. the beer bottle in clear and amber; the H&H Crystalvac jar in clear and amber, the amber worth roughly three times the clear).
The collectors. Two independent Three Rivers find-lists compiled by George West collectors (Hazel R. Gattis and Mrs. R. Y. Williams, preserved in Thelma Lindholm’s marker research) catalogue dozens of marked pieces — fruit jars, pickle jars, Crystalvac jars, peanut-butter jars, milk bottles, beer bottles, pepper-sauce bottles — as (clear), with only a couple of (Amber) items (an amber Crystalvac jar, an amber beer bottle). No green, blue, or other color appears.

Amber — the one functional color

Amber was not decorative; it was for light protection. Amber glass (carbon + sulfur reacting with iron in the melt) blocks essentially all UV and blue light below ~450 nm — the wavelengths that “skunk” beer and degrade other light-sensitive contents. A general bottle house therefore ran an amber tank alongside its flint tank, using amber for beer and similar ware and flint for everything where clarity mattered (soda/mineral water, food packers’ jars, medicine). Amber examples are scarcer and, among collectors, more prized — the amber H&H Crystalvac jar is the single most valuable standard item in Smith’s catalog.

Three misreadings to avoid

“Aqua” is not a Three Rivers color. Aqua/aquamarine is the natural, un-decolorized tint of ordinary iron-bearing glass — what you get by not decolorizing — not a deliberately produced color. Where Bill Lockhart’s El Paso research states the color of a Three Rivers-marked bottle, it is colorless: the Victory Bottling Works bottle’s “first three [variations] were all aqua,” but “the final variation … was colorless” and carried the 3 RIVERS ★ mark; the Union Bottling Works Three Rivers bottle is likewise colorless (“smokey”). A faintly aqua-tinted Three Rivers piece is under-decolorized flint, not a distinct color line.
The “green glass” line is about the sand, not the factory. A 1932 Geology of Texas passage (quoted in the marker research) says the local Carrizo sand “fuses to produce clear, green glass suitable for the manufacture of bottles.” That describes the raw material’s potential, not Three Rivers’ actual output — the factory’s documented output was flint and amber.
An “olive jar” is a shape, not a color. The collector lists include an “olive jar” (and elsewhere a “Clear, Small Olive Jar”) — a jar for packing olives, made in clear glass, not olive-green glass.

Amethyst? Almost certainly not production

A single online marketplace listing was paraphrased as “amethyst,” but it could not be verified and is best explained as sun-colored amethyst (SCA) — ordinary colorless glass that has purpled under long UV exposure — which the collector community warns is routinely over-hyped for this mark. SCA comes from a manganese decolorizer, and Three Rivers started up in 1922, after the manganese era (~1880–1917); by its time the industry decolorizer was selenium (with cobalt), which does not solarize to purple the same way. So even sun-purpling is less likely here, and no intentional amethyst production is attested.

Why the palette was narrow (glassmaking context)

The flint-plus-amber palette is exactly what standard 1920s–30s bottle-house chemistry and economics predict:

Flint required decolorizing, not just pure sand. Untreated soda-lime glass is green/aqua from iron in the sand; colorless glass needs a decolorizer (selenium + cobalt was the industry standard c.1912–1950s, Three Rivers’ whole era). Three Rivers’ advertised Carrizo sand purity mattered because it meant less decolorizer was needed to hit true flint — a genuine cost/quality edge — but the chemistry, not the sand alone, is what made colorless glass viable.
Greens, blues, and cobalt were niche. Those served small specialty markets (poisons, cosmetics). Tank furnaces ran continuously on one color and changing color wasted batch and fuel, so a general packers’/beverage house had no economic reason to run a third specialty-color tank.

The underlying color chemistry is drawn from the SHA/Lindsey glass-color reference (Bottle/Glass Colors).

Bottom line

Flint (colorless) and amber — that’s the documented Three Rivers palette. Everything else is either a misread of natural tint (aqua), a statement about the sand rather than the glass (green), a jar shape (olive), or unverified seller labeling / sun-purpling (amethyst). If a genuinely green, blue, cobalt, or milk-glass Three Rivers-marked piece ever surfaced with a clear mark, it would be a notable and undocumented exception — none is on record.