紅(hong)絲(si)石(shi)(shi)形(xing)成(cheng)(cheng)(cheng)于(yu)距(ju)今約4.5~5億年(nian)的(de)(de)早古時代,屬(shu)淺海(hai)一(yi)一(yi)陸臺潮坪相沉(chen)(chen)積(ji)巖(yan)(yan),巖(yan)(yan)性為(wei)泥質(zhi)白云質(zhi)粉(fen)晶(jing)灰巖(yan)(yan)。礦(kuang)物(wu)成(cheng)(cheng)(cheng)分主要為(wei)方解石(shi)(shi)組成(cheng)(cheng)(cheng),方解石(shi)(shi)含(han)量達94~98%,另含(han)少量鐵、錳及(ji)微量石(shi)(shi)英、云母(mu)等礦(kuang)物(wu)和泥質(zhi)物(wu)。蘊存于(yu)沉(chen)(chen)積(ji)碳酸鹽巖(yan)(yan)系中,多呈透鏡狀或扁豆狀,單(dan)體規模不大,一(yi)般厚(hou)5~20cm。紅(hong)絲(si)石(shi)(shi)是在(zai)特殊的(de)(de)沉(chen)(chen)積(ji)環境下形(xing)成(cheng)(cheng)(cheng)的(de)(de),即在(zai)局部(bu)地段出現沉(chen)(chen)積(ji)間(jian)斷(duan)之后(hou)露出地表,經風雨沖(chong)刷(shua)等外力作用下,變成(cheng)(cheng)(cheng)形(xing)態各異的(de)(de)洼地和小(xiao)丘(qiu),并(bing)接(jie)受陸源沉(chen)(chen)積(ji)物(wu)在(zai)密集的(de)(de)小(xiao)丘(qiu)間(jian)逐次成(cheng)(cheng)(cheng)層沉(chen)(chen)淀(dian),直到海(hai)侵以后(hou)的(de)(de)巨厚(hou)沉(chen)(chen)積(ji)成(cheng)(cheng)(cheng)巖(yan)(yan)。
紅(hong)絲石敲(qiao)擊聲(sheng)很脆(cui),無厚料,從側面看層(ceng)狀沉積(ji)巖特(te)征明顯,紅(hong)黃相間,正面出現(xian)像樹木年輪一樣的紅(hong)絲。紅(hong)絲石屬微晶(jing)質灰巖,顆粒均勻(yun),石質致密細膩,硬度約4度左右。
紅絲(si)石(shi),產(chan)于山(shan)(shan)(shan)東省青(qing)州市(shi)邵莊鎮的(de)黑(hei)山(shan)(shan)(shan)頂峰石(shi)洞中和臨朐縣(xian)冶源(yuan)(yuan)鎮老崖崮村(cun)的(de)壯山(shan)(shan)(shan)周圍。黑(hei)山(shan)(shan)(shan)和壯山(shan)(shan)(shan)兩地直線距離約二十公里(li),兩地所(suo)產(chan)之石(shi)色澤質地極(ji)為相似,系同出一脈。黑(hei)山(shan)(shan)(shan)因石(shi)源(yuan)(yuan)枯竭(jie),藏量甚(shen)少(shao),現紅絲(si)石(shi)多為壯山(shan)(shan)(shan)一帶所(suo)產(chan)。因古代臨朐縣(xian)隸(li)屬青(qing)州府,故以往統(tong)稱為青(qing)州紅絲(si)石(shi)。
紅(hong)絲(si)石(shi)屬微晶質(zhi)灰巖,顆粒均勻(yun),石(shi)質(zhi)致(zhi)密細膩,硬度(du)(du)約4度(du)(du)左右。色彩豐富(fu),常見(jian)有黃地(di)(di)紅(hong)絲(si)、紅(hong)地(di)(di)黃絲(si)、紫紅(hong)地(di)(di)褐絲(si)、紅(hong)褐地(di)(di)紫絲(si)、紫地(di)(di)黃絲(si)、紫地(di)(di)黑絲(si)等,尤以黃地(di)(di)紅(hong)絲(si)、紫地(di)(di)黑絲(si)者為佳。石(shi)上垂直剖(pou)面(mian)的(de)紋(wen)(wen)(wen)理基本平行,含(han)有后期構(gou)造裂隙影響所構(gou)成(cheng)的(de)錯斷或斜交,層面(mian)上的(de)紋(wen)(wen)(wen)理則(ze)千(qian)回百轉(zhuan),層次(ci)分明,尤似天然云紋(wen)(wen)(wen)、水(shui)紋(wen)(wen)(wen)、刷絲(si)紋(wen)(wen)(wen)等,千(qian)姿百態(tai)。石(shi)內絲(si)紋(wen)(wen)(wen)多者達十多層,且紋(wen)(wen)(wen)理變幻無窮,天然形(xing)成(cheng)山水(shui)草木、陽光(guang)月(yue)暈,人物鳥獸等狀,瑰麗多姿,獨具特(te)色,可(ke)制作成(cheng)高品(pin)位的(de)觀賞石(shi)。
紅(hong)絲石(shi)作為觀賞石(shi),主(zhu)要分(fen)兩類:一類是(shi)自然形(xing)紅(hong)絲石(shi),即(ji)天然形(xing)成,獨立成塊,不經為加工的紅(hong)絲石(shi);二是(shi)磨制后(hou)的紅(hong)絲硯(yan)賞石(shi),石(shi)質(zhi)細膩,膏(gao)潤(run)華澤(ze),紅(hong)黃(huang)顏(yan)色對比鮮明,絲紋變(bian)化豐富(fu)。
這(zhe)種石(shi)(shi)(shi)頭(tou)在宋朝(chao)就已經面臨枯竭,原因是它的(de)質地(di)適合制造硯臺,由于其特(te)殊材質,使(shi)得紅(hong)絲石(shi)(shi)(shi)硯不漬磨,不損(sun)毫,文人墨客推崇的(de)紅(hong)絲石(shi)(shi)(shi)硯臺居四大名硯之首,隨(sui)著紅(hong)絲石(shi)(shi)(shi)資(zi)源的(de)日(ri)漸減少,那些具有(you)悠(you)遠文化氣息的(de)硯臺作品連連升值。