Radiometric dating is worthless, and that fact is established by blind studies... something that is foreign to those who swallow evo-koolaid.
Example: 10 year old samples from Mt. St. Helens were radiometrically dated to over 300,000 years old.
I would say that a 30,000 fold margin of error = worthless.
Because radiometric dating utterly refutes their biblical interpretations, young-Earth creationists (YECs) are desperate to undermine the reality of these methods. As part of their efforts, YEC Dr. Steve Austin and his associates at the Institute for Creation 'Research'(ICR) collected a dacite sample from Mt. St. Helens, Washington State, USA, which probably erupted in 1986 AD. Austin et al. then ineffectively separated the sample into several mineral and glass 'fractions', submitted the dacite and its 'fractions' for potassium 40-argon 40 (K-Ar) dating, and subsequently used the bogus results to inappropriately attack the K-Ar method. Austin's conclusions on this project are summarized at the ICR website.
The 'research' efforts of Austin and his colleagues and their 'expertise' in radiometric dating have been widely criticized, including by Joe Meert (also here), Karen Bartelt and company and myself at No Answers in Genesis and in my web debate with Dr. David Plaisted at Tim Thompson's 'A Radiometric Dating Resource List'
AUSTIN FAILED TO PROPERLY USE THE K-Ar METHOD
Considering that the half-life of potassium-40 (40K) is fairly long (1,250 million years, McDougall and Harrison, 1999, p. 9), the K-Ar method cannot be used to date samples that are much younger than 6,000 years old (Dalrymple, 1991, p. 93). Considering the statements at the Geochron website and the lowest age limitations of the K-Ar method, why did Austin submit a recently erupted dacite to this laboratory and expect a reliable answer??? Contrary to Swenson's uninformed claim that ' Dr Austin carefully designed the research to counter all possible objections', Austin clearly demonstrated his inexperience in geochronology when he wasted a lot of money using the K-Ar method on the wrong type of samples.
Figure 4 in Austin's report, by itself, indicates that ancient zoned grains (phenocrysts and perhaps some xenocrysts) were common in Austin's dacite from Mt. St. Helens. It's also obvious from Austin's text that he was unsuccessful in adequately separating the volcanic glass from the much older minerals. Austin should have known that if he wanted to date the 1986 AD eruption the phenocrysts needed to be entirely removed from his 'fractions' and that another method besides K-Ar dating would have been required. Furthermore, when Austin submitted his samples to Geochron Laboratories, he failed to heed warnings from the laboratory about the limitations of their equipment. Both Austin and Swenson ignored the implications of zoned minerals and Bowen's Reaction Series on the age of the dacite. Obviously, it's Austin's improper use of the K-Ar method and not the method itself that is flawed. Rather than recognizing the flaws in Austin's essay, Swenson simply parrots Austin's erroneous claims without really understanding the chemistry and mineralogy of dacites.
MUCH More at link above