There are few natural sources of radiation that are powerful enough to register as anything anomalous to human beings (at least, during the time of human existence — ruling out things like the Oklo reactor over a billion years ago). Prior to the late-19th century, there just aren't sources people are going to notice, that are going to stand out.

Radioactivity was discovered through two main avenues. One was artificially creating radioactive rays through devices like the cathode-ray tube (late 19th century), which emerged out of studies of electrical phenomena. This is what led to the discovery of X-rays (Roentgen) and electrons (Thomson).

The other is the discovery that there were natural emissions in certain types of ores, notably uranium. This was figured out through the use of photographic emulsions in the late-19th century (Becquerel), and eventually led to the isolation of highly-radioactive substances in the early-20th century (Curie).

The tubes make radiation's effects pretty visible — you can literally burn yourself with them, and X-ray operators could be identified by their mangled hands (NSFL warning). The isolation/concentration of substances like radium makes for an impressive spectacle, because the resulting substances can glow in the dark and give out measurable heat.

Where else might you find evidence of radioactivity's effects? If you knew what you were looking for, you could find it in detrimental health effects of people who worked with radioactive sources. The miners of the Joachimsthal uranium mine, the first major source of uranium ores, had a much lower life-expectancy than even other hard rock miners, coming down with characteristic lung cancers that we now understand are related to exposure to radon gas. These lung diseases were described locally as "Bergkrankheit" (mountain sickness), and were described as early as the 16th century as a persistent cough that presents in miners who have spent a decade in the job. It was identified as a form of lung cancer only in 1879. The fact that it was related to radioactivity was not figured out until the early 20th century, and even then, there was plenty of uncertainty about the exact mechanism of the disease until the mid-20th century. (Egon Lorentz, "Radioactivity and Lung Cancer: A Critical Review of Lung Cancer in the Miners of Schneeberg and Joachimsthal," 1944.)

So in a sense, you can think of that as a misconstrued reference to radioactivity — but it's a bit of a stretch.

Human beings have long been fascinated by rays of light and energy, and the later discovery of radioactivity definitely "hooked into" cultural tropes along these lines. But the rays in question are from the Sun (a form of radiation, to be sure, though we are talking about visible spectrum and not the ionizing radiation), so I don't know whether that counts for your purposes. Weart's Nuclear Fear (1988) talks about these early, pre-radiation tropes that radiation fit into nicely.