to recall other facets of his location procedure (Tr. 122, 140, 192, 221, 243-44, 859). In addition, when asked at the hearing to identify three sets of photographs, Exhibits B-66, B-67, and B-68, Zweifel replied: A. I hesitate to state at this late stage. This has been four years, and I hesitate to attempt to identify it. I staked a number of claims and we are not going to get tangled up in a little thing like that. We have several thousand pictures. (Tr. 128.) Q. Do you recognize these pictures? A. I doubt if I could pick them out among thousands of pictures we have taken. I probably could, but I am not going to take a chance at it. I will put it like that. I have several thousand others and they all look almost the same. It is not a requirement of mining law to take pictures. We do that as an added precaution, as you know. (Tr. 129.) The photographs (Exh. C-13 through C-70) are completely lacking in probative value. They do not support the contention that the claims were located in accordance with the mining law. They substantiate only the fact that they were taken. At the hearing Zweifel was questioned as to the possibility of locating the same land twice. He replied: A. No, I don't think there is that possibility there. It might have occurred but I don't recall of knowing of the circumstances of that nature. Q. If you are really careful it probably wouldn't happen, is that right? A. I think it wouldn't happen. (Tr. 128.) Zweifel also stated that he checked the lands prior to locating and saw no indication of other staking (Tr. 290). When confronted with the fact that he had top filed in more than 200 separate instances (Exh. B-92), Zweifel had no explanation (Tr. 313). Zweifel testified that he located all the claims in contest without any assistance (Tr. 714). Yet between May 2 and May 23, 1966, Exhibits B-1 and B-2 show Zweifel purportedly located a total of 2063 claims in Colorado covering over 287,000 acres of land. On May 15, 1966, at the same time that Zweifel filed location notices for 497 mining claims in Rio Blanco County, Colorado (Exh. B-1 and B-2), he also filed location notices for 73 mining claims in Sweetwater County, Wyoming (Tr. 534, Exh. B-100). The record reveals the impossibility of the task purportedly undertaken by Zweifel. Judge Luoma concluded at page 27 of his decision: It is obvious from Mr. Zweifel's own testimony and pictures that his efforts, in addition to filing claim notices in the courthouse, were basically directed at posting notices or identification markers, on groups of claims, not on individual claims. He made no effort to establish individual claim corner monuments nor to ascertain whether the individual claims were in fact monumented by the public land surveys. In fact, an exercise in simple arithmetic would reveal the impossibility of a person's being able to set foot and post a notice on each one of the numerous claims within the time limitations fixed by Mr. Zweifel's activities. Furthermore, it defies belief that a person could find his way to each and every claim, considering the nature of the terrain and roads, the lack of fence lines, the disregard of survey monuments, and the navigational tools utilized by Mr. Zweifel. The finding is inescapable that Mr. Zweifel did not and could not post a claim May 29, 1973 notice on each and every claim so as to serve notice on the world that the land embraced thereby was under claim. Although we realize that Zweifel could have properly staked, posted notice upon and located some of the claims in contest, the burden rests with appellants to establish which of the claims, if any, were properly located. This burden appellants have not met. Appellants failed to comply with the federal mining law in the location of their 2,910 placer mining claims, Therefore, the claims are invalid. Burden of Proof In arguing that the Government has the burden of proof in a mining contest, appellants are incorrect as to the law. It is well settled that in a mining contest the Government has the burden of establishing a prima facie case that the mining claim is invalid. The claimant then must prove by a preponderance of evidence that his claim is valid. Foster v. Seaton, 271 F.2d 836 (D.C. Cir. 1959). Appellants contend that such a rule has developed only because of a misinterpretation of the Foster holding. The rule, however, has been consistently followed by the Department, United States v. Harper, 8 IBLA 357 (1972); United States v. Taylor, 8 IBLA 264 (1972); United States v. Bass, 6 IBLA 113 (1972), and by the courts, Converse v. Udall, supra; United States v. Toole, 224 F. Supp. 440 (1963). Appellants charge that the Government did not follow Departmental standards for the examination of placer mining claims. Appellants overlook the fact that such standards are merely general guidelines and do not have the force and effect of statutes or regulations. There is no requirement that such guidelines be followed. Whether or not they were followed is not the essential issue. It is, rather, whether or not the Government established a prima facie case that the claims are invalid. In the proper circumstances the Government may establish a prima facie case even though its witnesses were not physically present on the mining claims. United States v. Fischer Contracting Co., John T. Katsenes, Intervenor, A-28779 (August 21, 1962). Government witnesses herein testified, as set forth supra, that they were familiar with the subject area; that 98,000 to 99,000 oil shale samples had been taken in the area of the claims; that such samples had been analyzed to determine the minerals present; and that although alumina-bearing compounds were found, there was no known present process by which aluminum could be extracted from such compounds and marketed at a profit. Even though the Government witnesses were not physically present on each claim, their testimony, coupled with the testimony of Zweifel, is sufficient to establish the Government's prima facie case. As part of the prima facie case, the Government called Zweifel as an adverse witness. Zweifel was asked to state under oath what he did to locate the claims (Tr. 120, 145, 186-213, 240) and to discover a valuable mineral deposit on each claim (Tr. 144, 225, 231, 247, 715, 735-37). Zweifel's testimony as to location was so superficial and so implausible that it was reasonable for the Judge to conclude from that testimony and the testimony of other witnesses, that none of the claims were located according to the requirements of the mining law. See Adair v. Shallenberger, 119 F.2d 1017, 1019 (7th Cir. 1941). As to discovery, Zweifel is not an experienced assayer, metallurgist, chemist, engineer or surveyor. (Tr. 117, 246.) He testified that he had taken surface samples from every claim, but that none were identified to any particular claim (Tr. 715). Only approximately 20 of the samples were assayed. None of the assays could be related to any specific claim and none of the assays showed the existence of any valuable minerals which could be extracted and marketed at a profit. Again, considering the inherent implausibility of the Zweifel testimony concerning discovery, it was reasonable for the Judge to conclude from such testimony and the testimony of the Government witnesses that there was no discovery of an economically recoverable mineral on any of the claims herein. We find that the Government presented a prima facie case on both allegations in the complaint. The Government's prima facie case having been established, appellants had the responsibility of proving that the claims were located according to the mining law and that there was a discovery of a valuable mineral deposit on each claim. Appellants have failed to produce persuasive evidence that any claim was located properly or that there was a discovery on any claim. Default of Certain Contestees Appellants contend that the failure of some contestees to file answers to the complaint was cured by the answer as filed by Zweifel. The contestees against whom the judgment was rendered may not rely upon the answer filed by Zweifel, as his answer never purported to be on their behalf. United States v. Holcomb, A-31019 (August 21, 1969). The rules of practice of the Department governing procedures in contest proceedings provide that, within 30 days after service of the complaint a contestee must file in the office where the contest is pending an answer specifically meeting and responding to the allegations of the complaint. 43 CFR 4.450-6. The rules provide further that: If an answer is not filed as required, the allegations of the complaint will be taken as admitted by the contestee and the Manager will decide the case without a hearing. 43 CFR 4.450–7(a). On February 17, 1970, acting pursuant to the rules, the Colorado Land Office Manager issued a decision declaring the interests in the mining claims of the defaulting con May 29, 1973 testees named therein null and void for failure to answer the charges of the complaint. The only appeal taken from that decision was by John C. Sterge, a named contestee, which appeal related to additional interests acquired by him in the King Midas claims 1-7 and Westwood claims 1-7. Sterge also owned other claims and filed a timely answer. That answer is deemed to relate to all claims in which he had an interest, and his appeal herein is likewise deemed to encompass his interest in all such claims. The separate appeal is therefore moot. No other defaulting contestee appealed the Land Office Manager's decision. As to those contestees, the allegations in the complaint were deemed admitted and the decision of the Manager was proper. No timely appeal having been taken therefrom, the contest against the defaulting contestees is considered to be closed. In the Notice of Appeal filed in the present case by Kenneth Kienzle, Jr., such notice purports to be on behalf of "the contestees in Colorado Contest 441." As to defaulting contestees who did not file a timely appeal from the February 17, 1970, decision, the present appeal is dismissed pursuant to 43 CFR 4.411(b). Due Process Appellants' assertion that they were deprived of property without due process of law and without just compensation is without merit. Due process requires notice and oppor tunity for hearing. As to mining claims, it does not require that the hearing be held in the courts or forbid inquiry and determination by the Department. Best v. Humboldt Placer Mining Co., supra, at 338. Until the issuance of a patent, the legal title to a mining claim remains with the United States Government and the Department is empowered, after proper notice and adequate hearing, to determine the validity of the claim. Davis v. Nelson, 329 F.2d 840, 846 (9th Cir. 1964); Cameron v. United States, 252 U.S. 450, 459-60 (1920). Appellants argue that they did not receive a fair hearing. They allege that there was sufficient adverse publicity surrounding the contest proceeding so as to render a fair hearing impossible. They also charge that they were denied due process because of the bias and predisposition of the Administrative Law Judge and other Department of the Interior employees. They argue that such individuals should have been disqualified from participating in the adjudicatory proceedings. Appellants who were represented by Clement Theodore Cooper, Esq., made these same arguments in motions to disqualify and suspend the proceedings before the hearing. The Administrative Law Judge denied the motions by order dated May 13, 1970. Mr. Cooper renewed the motions at the hearing (Tr. 6-7). Appellants contend that before the contest proceeding the Depart ment of the Interior issued a number of statements to the news media implying that judgment had already been passed on the validity of the claims. Although, appellants have made general allegations of adverse prehearing publicity, they have failed to present any persuasive evidence that there was any unfairness in the contest proceeding itself. See United States v. Gunn, 7 IBLA 237, 246, 79 I.D. 588, 592 (1972). Appellants motion for disqualification on the concept that an Administrative Law Judge is an "employee" of the Department of the Interior and therefore subject to Departmental control. The relationship itself does not prove that the hearing was unfair or lacking in due process. United States v. Gunn, supra. In order to disqualify an Administrative Law Judge or justify a ruling that the hearing was unfair upon a charge of bias, there must be a substantial showing of bias. Converse v. Udall, supra; United States ex rel. DeLuca v. O'Rourke, 213 F.2d 759, 763 (8th Cir. 1954); United States v. Cody, 1 IBLA 92 (1970). In addition, the Departmental procedure in initiating, prosecuting and deciding mining contests does not violate that section of the Administrative Procedure Act, 5 U.S.C. § 554 (1970), which requires the separation of the investigative or prosecuting functions from those of decision making. United States v. Avgeris, 8 IBLA 316, 322 (1972); United States v. Mullin, 2 IBLA grounded their 133, 139 (1971); United States v. Melluzzo, 76 I.D. 160, 180-81 (1969). Clearly, appellants were not denied due process nor can we find support in the record for appellants' allegations that adverse publicity and bias rendered a fair hearing impossible. The Judge did not err in denying appellants' motions to disqualify himself and to suspend the proceedings. Prehearing Conference Appellants also maintain that the failure of the Judge to direct a prehearing conference was prejudicial error and an abuse of discretion. Under 43 CFR 4.430, the Administrative Law Judge may in his own discretion, on his own motion or motion of one of the parties, direct that a prehearing conference be held. The regulation clearly states that the decision of whether or not to hold a prehearing conference is discretionary with the Administrative Law Judge. In the present case, appellants did not make a motion to hold a prehearing conference, yet they assert that the failure of the Judge to order such a conference on his own motion was an abuse of discretion. To constitute an abuse of discretion the action must be arbitrary, fanciful, or clearly unreasonable. United States v. McWilliams, 163 F.2d 695, 697 (D.C. Cir. 1947). Appellants present no evidence that the failure to order a conference by Judge Luoma was arbitrary or clearly unreasonable. In addition, while the issues were being framed |